fix tgamma for inifity

* configure.in: do not use buggy tgamma() of mingw.

* missing/tgamma.c (tgamma): merge fix for inifity from
  ruby_tgamma.  since msvcr120.dll and later have tgamma, this
  implementation will not be used.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58691 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 0 insertions, 16 deletions

diff --git a/math.c b/math.c
index 245cdcfb01..570776baef 100644
--- a/math.c
+++ b/math.c
@@ -778,22 +778,6 @@ math_erfc(VALUE unused_obj, VALUE x)
     return DBL2NUM(erfc(Get_Double(x)));
 }
 
-#if defined _WIN32
-static inline double
-ruby_tgamma(const double d)
-{
-    const double g = tgamma(d);
-    if (isinf(g)) {
-	if (d == 0.0 && signbit(d)) return -INFINITY;
-    }
-    if (isnan(g)) {
-	if (!signbit(d)) return INFINITY;
-    }
-    return g;
-}
-#define tgamma(d) ruby_tgamma(d)
-#endif
-
 #if defined LGAMMA_R_PM0_FIX
 static inline double
 ruby_lgamma_r(const double d, int *sign)