The plain Makefile was using -Wall, but the gyp build wasn't. This CL turns on

The plain Makefile was using -Wall, but the gyp build wasn't.  This CL turns on
-Wall -Wextra and -Wno-unused in common.gypi.  This revealed a lot of warnings
(and some actual bugs), all of which I fixed here.  This is pretty mindless
stuff for the most part (order of intialization, missing initializers, && within
||, etc), but will allow us to build cleanly with -Wall and -Wextra (and
-Werror, if we so choose).

I put defaults into switches that were missing cases.  I could put in the actual
missing enums instead if that's desired.  I could also assert on missing enums
instead of break, if that's desired.  I wasn't sure how to test the stuff in
"animator", so that should be looked at a bit more closely.

Review URL:  http://codereview.appspot.com/4547055/

git-svn-id: http://skia.googlecode.com/svn/trunk@1386 2bbb7eff-a529-9590-31e7-b0007b416f81