hide SkBitmap::setConfig

patch from issue 325733002

TBR=scroggo

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/322963002
diff --git a/src/ports/SkImageDecoder_CG.cpp b/src/ports/SkImageDecoder_CG.cpp
index a21536b..8545ac8 100644
--- a/src/ports/SkImageDecoder_CG.cpp
+++ b/src/ports/SkImageDecoder_CG.cpp
@@ -68,9 +68,8 @@
 
     const int width = SkToInt(CGImageGetWidth(image));
     const int height = SkToInt(CGImageGetHeight(image));
-    SkImageInfo skinfo = SkImageInfo::MakeN32Premul(width, height);
 
-    bm->setInfo(skinfo);
+    bm->setInfo(SkImageInfo::MakeN32Premul(width, height));
     if (SkImageDecoder::kDecodeBounds_Mode == mode) {
         return true;
     }