merge revision(s) 36820: [Backport #7550]
mkmf.rb: clean timestamps * lib/mkmf.rb (MakeMakefile::CLEANINGS): clean timestamp files.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@38528 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 36820: [Backport #7550]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@38528 b2dd03c8-39d4-4d8f-98ff-823fe69b080e