Fix warning about math functions, include isnan, isinf, fpclassify.

src/nvim/strings.c

@@ -50,6 +50,18 @@
 #include "nvim/os/shell.h"
 #include "nvim/eval/encode.h"
 
+/*
+ * Fix warning on mingw32 and mingw64
+ * make isnan as _isnan
+ * fpclassify is used by isinf, so redefine it
+ */
+#ifdef __MINGW32__
+# undef fpclassify
+# define fpclassify __fpclassify
+# undef isnan
+# define isnan _isnan
+#endif
+
 /*
  * Copy "string" into newly allocated memory.
  */