* bignum.c, include/ruby/intern.h (rb_big_eql): exported.

	* thread.c (recursive_check): object_id maybe a Bignum, not Fixnum on
	  LLP64.  see also r38493 and r38548.
	  reported by Heesob Park at [ruby-core:51083] [Bug #7607], and patched
	  by shirosaki at [ruby-core:51095]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@38598 b2dd03c8-39d4-4d8f-98ff-823fe69b080e