Ruby » Ruby master

merge revision(s) 62007,62024: [Backport #13069]

    mkmf.rb: ignore linker warnings

    * lib/mkmf.rb (try_ldflags): ignore linker warnings.  they cause
      unexpected failures on OpenBSD.  [ruby-core:78827] [Bug #13069]

    mkmf.rb: werror on mswin

    * lib/mkmf.rb (MakeMakefile#try_ldflags): enable warning checking
      on mswin, link.exe warns -l options but does not fail.
      [Bug #13069]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@65117 b2dd03c8-39d4-4d8f-98ff-823fe69b080e