mkmf: Unquote directory strings

* lib/mkmf.rb (find_executable0): On Windows, it is actually valid
  to surround individual PATH directory entries with double
  quotes. Remove these before joining the path as otherwise the
  literal quotes would become part of the path, resulting in the
  executable not to be found.  [Fix GH-1305]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54255 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,11 @@
+Fri Mar 25 01:10:42 2016  Sebastian Schuberth  <sschuberth@gmail.com>
+
+	* lib/mkmf.rb (find_executable0): On Windows, it is actually valid
+	  to surround individual PATH directory entries with double
+	  quotes. Remove these before joining the path as otherwise the
+	  literal quotes would become part of the path, resulting in the
+	  executable not to be found.  [Fix GH-1305]
+
 Thu Mar 24 22:38:18 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* strftime.c (FMT, FMTV): remove recursive-assignments to get rid

lib/mkmf.rb

@@ -1551,6 +1551,7 @@ SRC
     end
     file = nil
     path.each do |dir|
+      dir.sub!(/\A"(.*)"\z/m, '\1') if $mswin or $mingw
       return file if executable_file.call(file = File.join(dir, bin))
       if exts
         exts.each {|ext| executable_file.call(ext = file + ext) and return ext}

test/mkmf/test_find_executable.rb

@@ -47,5 +47,12 @@ class TestMkmf
         assert_nil(result)
       end
     end
+
+    if /mingw|mswin/ =~ RUBY_PLATFORM
+      def test_quoted_path_on_windows
+        ENV["PATH"] = %["#{@tmpdir}"]
+        test_find_executable
+      end
+    end
   end
 end