FIX: suppress a signed/unsigned mismatch MSVC warning

Author: Oldes

src/core/f-qsort.c

@@ -200,6 +200,7 @@ loop:	SWAPINIT(a, es);
 	pn = (char *)a + n * es;
 	r = min(pa - (char *)a, pb - pa);
 	vecswap(a, pb - r, r);
+#pragma warning(suppress: 4018)
 	r = min(pd - pc, pn - pd - es);
 	vecswap(pb, pn - r, r);
 	if ((r = pb - pa) > es)