Add incomplet long double math support to libmingwex.a

winsup/mingw/mingwex/math/sqrtl.c

@@ -0,0 +1,8 @@
+#include <math.h>
+long double
+sqrtl (long double x)
+{
+  long double res;
+  asm ("fsqrt" : "=t" (res) : "0" (x));
+  return res;
+}