* missing/isinf.c (isinf): don't define if the macro is defined.
	* numeric.c (flodivmod): work around for infinity.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_6@16935 b2dd03c8-39d4-4d8f-98ff-823fe69b080e