merge revision(s) 51242: [Backport #11343]
* gc.c (__has_feature): move into internal.h. * internal.h (__has_feature): ditto. * internal.h (__has_extension): new macro. * internal.h (STATIC_ASSERT): use _Static_assert with clang. [ruby-core:69931] [Bug #11343]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@52778 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 51242: [Backport #11343]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@52778 b2dd03c8-39d4-4d8f-98ff-823fe69b080e