Issue#114: check for the presence of isnan and isinf, and provide compat macros on MSCV where _isnan and _finite exist instead.
diff --git a/config.h.in b/config.h.in
index e59a5a3..d612636 100644
--- a/config.h.in
+++ b/config.h.in
@@ -3,6 +3,22 @@
/* Define if .gnu.warning accepts long strings. */
#undef HAS_GNU_WARNING_LONG
+/* Define to 1 if you have the declaration of `isinf', and to 0 if you don't.
+ */
+#undef HAVE_DECL_ISINF
+
+/* Define to 1 if you have the declaration of `isnan', and to 0 if you don't.
+ */
+#undef HAVE_DECL_ISNAN
+
+/* Define to 1 if you have the declaration of `_finite', and to 0 if you
+ don't. */
+#undef HAVE_DECL__FINITE
+
+/* Define to 1 if you have the declaration of `_isnan', and to 0 if you don't.
+ */
+#undef HAVE_DECL__ISNAN
+
/* Define to 1 if you have the <dlfcn.h> header file. */
#undef HAVE_DLFCN_H