* configure.in (rb_cv_lgamma_r_pm0): check if lgamma_r(+0.0)
	  returns positive infinity, in addition to lgamma_r(-0.0).
	  AIX returns an incorrect result of negative infinity.

	* math.c (ruby_lgamma_r): handle +0.0, in addition to -0.0.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@62141 b2dd03c8-39d4-4d8f-98ff-823fe69b080e