* math.c (ruby_tgamma): fix tgamma(-0.0) on mingw.
[ruby-core:74817] [Bug #12249]
* math.c (ruby_lgamma_r): fix lgamma(-0.0) on mingw and OSX.
* math.c (ruby_lgamma_r): mswin's lgamma_r also seems to be wrong.
cf. [Bug #12249]
* math.c (ruby_lgamma_r): missing/lgamma_r.c is used on Windows,
since msvcrt does not provide it.
* missing/lgamma_r.c (lgamma_r): fix lgamma(-0.0).
[ruby-core:74823] [Bug #12249]
* configure.in (rb_cv_lgamma_r_m0): check if lgamma_r(-0.0)
returns negative infinity. [Bug #12249]
* math.c (ruby_lgamma_r): define by the configured result.
* configure.in (rb_cv_lgamma_r_m0): fix the condition for
lgamma_r(-0.0). [Bug #12249]
merge revision(s) 54492,54494,54495,54496,54499,54503: [Backport #12249]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@54643 b2dd03c8-39d4-4d8f-98ff-823fe69b080e