add suggested decode color type to colorspaceinfo

E.g.

~/skia (decode-as|✚1…) $ ninja -C out/ colorspaceinfo; and out/colorspaceinfo --input ~/Downloads/prophoto.png
    ninja: Entering directory `out/'
    [2/2] link colorspaceinfo
    SkCodec would naturally decode as colorType=RGBA_8888
    Color Profile Description:
    "Google/Skia/215028B4833C240E0583AFE600C80A79"
    ...

Change-Id: Id36efadaa84e9ffa5d67153e074be8a8426b6c42
Reviewed-on: https://skia-review.googlesource.com/26140
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

tools/colorspaceinfo.cpp

@@ -465,6 +465,8 @@ int main(int argc, char** argv) {
     } else {
         codec.reset(SkCodec::NewFromData(data));
         colorSpace = sk_ref_sp(codec->getInfo().colorSpace());
+        SkDebugf("SkCodec would naturally decode as colorType=%s\n",
+                 sk_tool_utils::colortype_name(codec->getInfo().colorType()));
     }
 
     if (!colorSpace) {