zip and bzip2 dependencies when needed

On some systems identified as Linux, zip and bzip2 might
not be available. Therefore, on such platforms we add them
unconditionally as dependencies when required. On Mac, these
dependencies are always satisfied.

Library/Homebrew/dependency_collector.rb

@@ -72,6 +72,14 @@ class DependencyCollector
 
   def ld64_dep_if_needed(*); end
 
+  def zip_dep_if_needed(tags)
+    return
+  end
+
+  def bzip2_dep_if_needed(tags)
+    return
+  end
+
   def self.tar_needs_xz_dependency?
     !new.xz_dep_if_needed([]).nil?
   end
@@ -162,6 +170,8 @@ class DependencyCollector
     when ".lz"          then Dependency.new("lzip", tags)
     when ".rar"         then Dependency.new("unrar", tags)
     when ".7z"          then Dependency.new("p7zip", tags)
+    when ".zip"         then zip_dep_if_needed(tags)
+    when ".bz2"         then bzip2_dep_if_needed(tags)
     end
   end
 end

Library/Homebrew/extend/os/dependency_collector.rb

@@ -1,2 +1,3 @@
 require "dependency_collector"
 require "extend/os/mac/dependency_collector" if OS.mac?
+require "extend/os/linux/dependency_collector" if OS.linux?

Library/Homebrew/extend/os/linux/dependency_collector.rb

@@ -0,0 +1,27 @@
+class DependencyCollector
+
+  def git_dep_if_needed(tags)
+    Dependency.new("git", tags)
+  end
+
+  def cvs_dep_if_needed(tags)
+    Dependency.new("cvs", tags)
+  end
+
+  def xz_dep_if_needed(tags)
+    Dependency.new("xz", tags)
+  end
+
+  def ld64_dep_if_needed(*)
+    return
+  end
+
+  def zip_dep_if_needed(tags)
+    Dependency.new("zip", tags)
+  end
+
+  def bzip2_dep_if_needed(tags)
+    Dependency.new("bzip2", tags)
+  end
+
+end

Library/Homebrew/extend/os/mac/dependency_collector.rb

@@ -23,4 +23,9 @@ class DependencyCollector
     return if MacOS.version > :tiger
     LD64Dependency.new
   end
+
+  def zip_dep_if_needed(tags); end
+
+  def bzip2_dep_if_needed(tags); end
+
 end