Fix bmp bug exposed by fuzzer

BUG=skia:5820
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2391933004

Review-Url: https://codereview.chromium.org/2391933004
diff --git a/src/codec/SkBmpRLECodec.cpp b/src/codec/SkBmpRLECodec.cpp
index 252d63e..dc5d689 100644
--- a/src/codec/SkBmpRLECodec.cpp
+++ b/src/codec/SkBmpRLECodec.cpp
@@ -451,6 +451,7 @@
                                 setRGBPixel(dst, dstRowBytes, dstInfo,
                                             x++, y, red, green, blue);
                                 numPixels--;
+                                break;
                             }
                             default:
                                 SkASSERT(false);