Fix segfaults on 32bit arch with --log-level=debug

There were a few improper uses of %ld for 64 bit numbers, as well as
some other 32 bit related warnings that I've fixed.

Signed-off-by: ktprograms <ktprograms@gmail.com>

src/backend/backend_common.c

@@ -92,7 +92,7 @@ make_shadow(xcb_connection_t *c, const conv *kernel, double opacity, int width,
 	}
 
 	unsigned char *data = ximage->data;
-	long sstride = ximage->stride;
+	long long sstride = ximage->stride;
 
 	// If the window body is smaller than the kernel, we do convolution directly
 	if (width < r * 2 && height < r * 2) {