use the bitmap stride when encoding a screenshot as PNG

Bug: 8444808
Change-Id: I47b74c22c940b40bd02634e9cd9dbff39b29a99f
diff --git a/cmds/screencap/screencap.cpp b/cmds/screencap/screencap.cpp
index e1270af..be32355 100644
--- a/cmds/screencap/screencap.cpp
+++ b/cmds/screencap/screencap.cpp
@@ -179,7 +179,7 @@
     if (base) {
         if (png) {
             SkBitmap b;
-            b.setConfig(flinger2skia(f), w, h);
+            b.setConfig(flinger2skia(f), w, h, s*bytesPerPixel(f));
             b.setPixels((void*)base);
             SkDynamicMemoryWStream stream;
             SkImageEncoder::EncodeStream(&stream, b,