Fix some more compiler warnings on armcc.

src/video/SDL_blit_A.c

@@ -1317,9 +1317,9 @@ SDL_CalculateBlitA(SDL_Surface * surface)
 
         case 3:
         default:
-            return BlitNtoNPixelAlpha;
+            break;
         }
-        break;
+        return BlitNtoNPixelAlpha;
 
     case SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
         if (sf->Amask == 0) {

src/video/SDL_bmp.c

@@ -124,6 +124,9 @@ SDL_LoadBMP_RW(SDL_RWops * src, int freesrc)
     Uint32 biClrUsed = 0;
     /* Uint32 biClrImportant = 0; */
 
+    (void) haveRGBMasks;
+    (void) haveAlphaMask;
+
     /* Make sure we are passed a valid data source */
     surface = NULL;
     was_error = SDL_FALSE;