dependency_collector: Fix ant_dep for Linux.

Signed-off-by: Bob W. Hogg <rwhogg@linux.com>

Library/Homebrew/dependency_collector.rb

@@ -136,7 +136,7 @@ class DependencyCollector
   end
 
   def ant_dep(spec, tags)
-    if MacOS.version >= :mavericks
+    if MacOS.version >= :mavericks || !OS.mac?
       Dependency.new(spec.to_s, tags)
     end
   end

Library/Homebrew/test/test_dependency_collector.rb

@@ -76,6 +76,20 @@ class DependencyCollectorTests < Homebrew::TestCase
     assert_predicate dep, :optional?
   end
 
+  def test_ant_dep_mavericks_or_newer
+    skip "Only for Mac OS" unless OS.mac?
+    MacOS.stubs(:version).returns(MacOS::Version.new("10.9"))
+    @d.add :ant => :build
+    assert_equal find_dependency("ant"), Dependency.new("ant", [:build])
+  end
+
+  def test_ant_dep_pre_mavericks
+    skip "Only for Mac OS" unless OS.mac?
+    MacOS.stubs(:version).returns(MacOS::Version.new("10.7"))
+    @d.add :ant => :build
+    assert_nil find_dependency("ant")
+  end
+
   def test_raises_typeerror_for_unknown_classes
     assert_raises(TypeError) { @d.add(Class.new) }
   end