rtextures: Fix ImageDraw() source clipping when drawing beyond top left (#3306)

src/rtextures.c

@@ -3481,7 +3481,7 @@ void ImageDraw(Image *dst, Image src, Rectangle srcRec, Rectangle dstRec, Color
         // Destination rectangle out-of-bounds security checks
         if (dstRec.x < 0)
         {
-            srcRec.x = -dstRec.x;
+            srcRec.x -= dstRec.x;
             srcRec.width += dstRec.x;
             dstRec.x = 0;
         }
@@ -3489,7 +3489,7 @@ void ImageDraw(Image *dst, Image src, Rectangle srcRec, Rectangle dstRec, Color
 
         if (dstRec.y < 0)
         {
-            srcRec.y = -dstRec.y;
+            srcRec.y -= dstRec.y;
             srcRec.height += dstRec.y;
             dstRec.y = 0;
         }