configure.in: define STDC_WANT_LIB_EXT1
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53252 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
configure.in: define STDC_WANT_LIB_EXT1
in strict C99 mode.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53252 b2dd03c8-39d4-4d8f-98ff-823fe69b080e