FIX: signed/unsigned mismatch warning

Author: Oldes

src/core/l-scan.c

@@ -555,7 +555,7 @@
 
 /***********************************************************************
 **
-*/  const REBYTE *Scan_Raw_String(const REBYTE *src, SCAN_STATE *scan_state, int num)
+*/  const REBYTE *Scan_Raw_String(const REBYTE *src, SCAN_STATE *scan_state, REBLEN num)
 /*
 **      Scan a raw string (without any modifications).
 **		Eliminates need of double escaping and allowes unmatched braces.

src/core/n-image.c

@@ -312,7 +312,7 @@ double weighted_rgb_color_distance(long r1, long g1, long b1, long r2, long g2,
 	} else {
 		pixels = VAL_IMAGE_WIDE(img1) * VAL_IMAGE_HIGH(img1);
 
-		for (int i = 0; i < pixels; i++, rgba1 += 4, rgba2 += 4) {
+		for (REBCNT i = 0; i < pixels; i++, rgba1 += 4, rgba2 += 4) {
 			dist += weighted_rgb_color_distance(
 				rgba1[C_R], rgba1[C_G], rgba1[C_B],
 				rgba2[C_R], rgba2[C_G], rgba2[C_B]

src/core/s-unicode.c

@@ -808,7 +808,7 @@ Boolean isLegalUTF8Sequence(const UTF8 *source, const UTF8 *sourceEnd) {
 		if (uni) {
 			// not using wcslen, because on some systems wchar_t has 4 bytes!
 			cnt = 0;
-			while (*up++ != 0 && cnt < max) cnt++;
+			while (*up++ != 0 && cnt < (REBLEN)max) cnt++;
 			up = (REBUNI*)src;
 		} else
 			cnt = LEN_BYTES(bp);