numeric.c: isfinite

* numeric.c (flo_is_finite_p): prefer C99 standard isfinite() than
  deprecated finite().

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44505 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -1883,6 +1883,7 @@ AC_CHECK_FUNCS(gettimeofday)		# for making ac_cv_func_gettimeofday
 AC_CHECK_FUNCS(gmtime_r)
 AC_CHECK_FUNCS(initgroups)
 AC_CHECK_FUNCS(ioctl)
+AC_CHECK_FUNCS(isfinite)
 AC_CHECK_FUNCS(issetugid)
 AC_CHECK_FUNCS(killpg)
 AC_CHECK_FUNCS(lchmod)

numeric.c

@@ -30,8 +30,12 @@
 #include <ieeefp.h>
 #endif
 
+#if !defined HAVE_ISFINITE && !defined isfinite
 #if defined HAVE_FINITE && !defined finite && !defined _WIN32
 extern int finite(double);
+# define HAVE_ISFINITE 1
+# define isfinite(x) finite(x)
+#endif
 #endif
 
 /* use IEEE 64bit values if not defined */
@@ -1457,8 +1461,8 @@ flo_is_finite_p(VALUE num)
 {
     double value = RFLOAT_VALUE(num);
 
-#if HAVE_FINITE
-    if (!finite(value))
+#if HAVE_ISFINITE
+    if (!isfinite(value))
 	return Qfalse;
 #else
     if (isinf(value) || isnan(value))