apr 1.5.1 (new formula)

Migrates Apr from Homebrew/Apache to Homebrew/Homebrew, adds a
requirement to allow people to use this Apr instead of requiring
people to download the full CLT package. Tested against subversion
with consistent success.

Closes Homebrew/homebrew#34987.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/requirements/apr_dependency.rb

@@ -0,0 +1,39 @@
+require "requirement"
+
+class AprDependency < Requirement
+  fatal true
+  default_formula "apr"
+
+  satisfy { MacOS::CLT.installed? || Formula["apr"].installed? }
+
+  env do
+    unless MacOS::CLT.installed?
+      ENV.prepend_path "PATH", "#{Formula["apr-util"].opt_prefix}/bin"
+      ENV.prepend_path "PKG_CONFIG_PATH", "#{Formula["apr"].opt_prefix}/libexec/lib/pkgconfig"
+      ENV.prepend_path "PKG_CONFIG_PATH", "#{Formula["apr-util"].opt_prefix}/libexec/lib/pkgconfig"
+    end
+  end
+
+  def message
+    message = <<-EOS.undent
+      Due to packaging problems on Apple's part, software that compiles
+      against APR requires the standalone Command Line Tools.
+    EOS
+    if MacOS.version >= :mavericks
+      message += <<-EOS.undent
+        Either
+        `brew install apr-util`
+        or
+        `xcode-select --install`
+        to install APR.
+      EOS
+    else
+      message += <<-EOS.undent
+        The standalone package can be obtained from
+        https://developer.apple.com/downloads/,
+        or it can be installed via Xcode's preferences.
+        Or you can `brew install apr-util`.
+      EOS
+    end
+  end
+end