Add incomplet long double math support to libmingwex.a

winsup/mingw/mingwex/math/fmax.c

@@ -0,0 +1,7 @@
+#include <math.h>
+
+double
+fmax (double _x, double _y)
+{
+   return ( isgreaterequal (_x, _y)|| __isnan (_y) ?  _x : _y );
+}