Fix fread() to return a correct value on platforms where sizeof(int) !=

sizeof(size_t), i.e. on all 64-bit platforms.

Reported by:	Andrey V. Elsukov
MFC after:	3 days

lib/libc/stdio/fread.c

@@ -50,7 +50,7 @@ __FBSDID("$FreeBSD$");
 size_t
 fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
 {
-	int ret;
+	size_t ret;
 
 	FLOCKFILE(fp);
 	ret = __fread(buf, size, count, fp);