Reference self rather than ENV in Superenv module

We want to be able to extend this module onto an arbitrary hash and use
it without mutating ENV, for testing purposes.

Library/Homebrew/superenv.rb

@@ -37,25 +37,25 @@ module Superenv
 
   def setup_build_environment
     reset
-    ENV['CC'] = 'cc'
+    self['CC'] = 'cc'
-    ENV['CXX'] = 'c++'
+    self['CXX'] = 'c++'
-    ENV['OBJC'] = 'cc'
+    self['OBJC'] = 'cc'
-    ENV['OBJCXX'] = 'c++'
+    self['OBJCXX'] = 'c++'
-    ENV['DEVELOPER_DIR'] = determine_developer_dir
+    self['DEVELOPER_DIR'] = determine_developer_dir
-    ENV['MAKEFLAGS'] ||= "-j#{determine_make_jobs}"
+    self['MAKEFLAGS'] ||= "-j#{determine_make_jobs}"
-    ENV['PATH'] = determine_path
+    self['PATH'] = determine_path
-    ENV['PKG_CONFIG_PATH'] = determine_pkg_config_path
+    self['PKG_CONFIG_PATH'] = determine_pkg_config_path
-    ENV['PKG_CONFIG_LIBDIR'] = determine_pkg_config_libdir
+    self['PKG_CONFIG_LIBDIR'] = determine_pkg_config_libdir
-    ENV['HOMEBREW_CC'] = determine_cc
+    self['HOMEBREW_CC'] = determine_cc
-    ENV['HOMEBREW_CCCFG'] = determine_cccfg
+    self['HOMEBREW_CCCFG'] = determine_cccfg
-    ENV['HOMEBREW_BREW_FILE'] = HOMEBREW_BREW_FILE
+    self['HOMEBREW_BREW_FILE'] = HOMEBREW_BREW_FILE
-    ENV['HOMEBREW_SDKROOT'] = "#{MacOS.sdk_path}" if MacOS::Xcode.without_clt?
+    self['HOMEBREW_SDKROOT'] = "#{MacOS.sdk_path}" if MacOS::Xcode.without_clt?
-    ENV['HOMEBREW_DEVELOPER_DIR'] = determine_developer_dir # used by our xcrun shim
+    self['HOMEBREW_DEVELOPER_DIR'] = determine_developer_dir # used by our xcrun shim
-    ENV['CMAKE_PREFIX_PATH'] = determine_cmake_prefix_path
+    self['CMAKE_PREFIX_PATH'] = determine_cmake_prefix_path
-    ENV['CMAKE_FRAMEWORK_PATH'] = determine_cmake_frameworks_path
+    self['CMAKE_FRAMEWORK_PATH'] = determine_cmake_frameworks_path
-    ENV['CMAKE_INCLUDE_PATH'] = determine_cmake_include_path
+    self['CMAKE_INCLUDE_PATH'] = determine_cmake_include_path
-    ENV['CMAKE_LIBRARY_PATH'] = determine_cmake_library_path
+    self['CMAKE_LIBRARY_PATH'] = determine_cmake_library_path
-    ENV['ACLOCAL_PATH'] = determine_aclocal_path
+    self['ACLOCAL_PATH'] = determine_aclocal_path
 
     # The HOMEBREW_CCCFG ENV variable is used by the ENV/cc tool to control
     # compiler flag stripping. It consists of a string of characters which act
@@ -75,14 +75,14 @@ module Superenv
 
     # Homebrew's apple-gcc42 will be outside the PATH in superenv,
     # so xcrun may not be able to find it
-    if ENV['HOMEBREW_CC'] == 'gcc-4.2'
+    if self['HOMEBREW_CC'] == 'gcc-4.2'
       apple_gcc42 = Formula.factory('apple-gcc42') rescue nil
-      ENV.append('PATH', apple_gcc42.opt_prefix/'bin', ':') if apple_gcc42
+      append('PATH', apple_gcc42.opt_prefix/'bin', ':') if apple_gcc42
     end
   end
 
   def universal_binary
-    ENV['HOMEBREW_ARCHS'] = Hardware::CPU.universal_archs.join(',')
+    self['HOMEBREW_ARCHS'] = Hardware::CPU.universal_archs.join(',')
     append 'HOMEBREW_CCCFG', "u", ''
   end
 
@@ -106,24 +106,24 @@ module Superenv
       "llvm-gcc"
     elsif ARGV.include? '--use-clang'
       "clang"
-    elsif ENV['HOMEBREW_USE_CLANG']
+    elsif self['HOMEBREW_USE_CLANG']
       opoo %{HOMEBREW_USE_CLANG is deprecated, use HOMEBREW_CC="clang" instead}
       "clang"
-    elsif ENV['HOMEBREW_USE_LLVM']
+    elsif self['HOMEBREW_USE_LLVM']
       opoo %{HOMEBREW_USE_LLVM is deprecated, use HOMEBREW_CC="llvm" instead}
       "llvm-gcc"
-    elsif ENV['HOMEBREW_USE_GCC']
+    elsif self['HOMEBREW_USE_GCC']
       opoo %{HOMEBREW_USE_GCC is deprecated, use HOMEBREW_CC="gcc" instead}
       "gcc"
-    elsif ENV['HOMEBREW_CC']
+    elsif self['HOMEBREW_CC']
-      case ENV['HOMEBREW_CC']
+      case self['HOMEBREW_CC']
-        when 'clang', 'gcc-4.0' then ENV['HOMEBREW_CC']
+        when 'clang', 'gcc-4.0' then self['HOMEBREW_CC']
         # depending on Xcode version plain 'gcc' could actually be
         # gcc-4.0 or llvm-gcc
         when 'gcc', 'gcc-4.2' then 'gcc-4.2'
         when 'llvm', 'llvm-gcc' then 'llvm-gcc'
       else
-        opoo "Invalid value for HOMEBREW_CC: #{ENV['HOMEBREW_CC'].inspect}"
+        opoo "Invalid value for HOMEBREW_CC: #{self['HOMEBREW_CC'].inspect}"
         default_cc
       end
     else
@@ -206,7 +206,7 @@ module Superenv
   end
 
   def determine_make_jobs
-    if (j = ENV['HOMEBREW_MAKE_JOBS'].to_i) < 1
+    if (j = self['HOMEBREW_MAKE_JOBS'].to_i) < 1
       Hardware::CPU.cores
     else
       j
@@ -237,7 +237,7 @@ module Superenv
     # If Xcode path is fucked then this is basically a fix. In the case where
     # nothing is valid, it still fixes most usage to supply a valid path that
     # is not "/".
-    MacOS::Xcode.prefix || ENV['DEVELOPER_DIR']
+    MacOS::Xcode.prefix || self['DEVELOPER_DIR']
   end
 
   public
@@ -251,12 +251,12 @@ module Superenv
 
 ### DEPRECATE THESE
   def compiler
-    case ENV['HOMEBREW_CC']
+    case self['HOMEBREW_CC']
       when "llvm-gcc" then :llvm
       when "gcc-4.2" then :gcc
-      when "gcc", "clang" then ENV['HOMEBREW_CC'].to_sym
+      when "gcc", "clang" then self['HOMEBREW_CC'].to_sym
     else
-      raise "Invalid value for HOMEBREW_CC: #{ENV['HOMEBREW_CC'].inspect}"
+      raise "Invalid value for HOMEBREW_CC: #{self['HOMEBREW_CC'].inspect}"
     end
   end
   def deparallelize
@@ -264,25 +264,25 @@ module Superenv
   end
   alias_method :j1, :deparallelize
   def gcc
-    ENV['CC'] = ENV['OBJC'] = ENV['HOMEBREW_CC'] = "gcc"
+    self['CC'] = self['OBJC'] = self['HOMEBREW_CC'] = "gcc"
-    ENV['CXX'] = ENV['OBJCXX'] = "g++-4.2"
+    self['CXX'] = self['OBJCXX'] = "g++-4.2"
   end
   def llvm
-    ENV['CC'] = ENV['OBJC'] = ENV['HOMEBREW_CC'] = "llvm-gcc"
+    self['CC'] = self['OBJC'] = self['HOMEBREW_CC'] = "llvm-gcc"
-    ENV['CXX'] = ENV['OBJCXX'] = "llvm-g++-4.2"
+    self['CXX'] = self['OBJCXX'] = "llvm-g++-4.2"
   end
   def clang
-    ENV['CC'] = ENV['OBJC'] = ENV['HOMEBREW_CC'] = "clang"
+    self['CC'] = self['OBJC'] = self['HOMEBREW_CC'] = "clang"
-    ENV['CXX'] = ENV['OBJCXX'] = "clang++"
+    self['CXX'] = self['OBJCXX'] = "clang++"
   end
   def make_jobs
-    ENV['MAKEFLAGS'] =~ /-\w*j(\d)+/
+    self['MAKEFLAGS'] =~ /-\w*j(\d)+/
     [$1.to_i, 1].max
   end
 
   # Many formula assume that CFLAGS etc. will not be nil.
   # This should be a safe hack to prevent that exception cropping up.
-  # Main consqeuence of this is that ENV['CFLAGS'] is never nil even when it
+  # Main consqeuence of this is that self['CFLAGS'] is never nil even when it
   # is which can break if checks, but we don't do such a check in our code.
   def [] key
     if has_key? key