fix warnings on Mac in src/images

Fix these class of warnings:
- unused functions
- unused locals
- sign mismatch
- missing function prototypes
- missing newline at end of file
- 64 to 32 bit truncation

The changes prefer to link in dead code in the debug build
with 'if (false)' than to comment it out, but trivial cases
are commented out or sometimes deleted if it appears to be
a copy/paste error.
Review URL: https://codereview.appspot.com/6299048

git-svn-id: http://skia.googlecode.com/svn/trunk@4179 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/images/SkImageDecoder_libico.cpp b/src/images/SkImageDecoder_libico.cpp
index 3473344..30611cb 100644
--- a/src/images/SkImageDecoder_libico.cpp
+++ b/src/images/SkImageDecoder_libico.cpp
@@ -24,9 +24,11 @@
     virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode);
 };
 
+#if 0 // UNUSED
 SkImageDecoder* SkCreateICOImageDecoder() {
     return new SkICOImageDecoder;
 }
+#endif
 
 /////////////////////////////////////////////////////////////////////////////////////////
 
@@ -372,7 +374,7 @@
 
 #include "SkTRegistry.h"
 
-SkImageDecoder* sk_libico_dfactory(SkStream* stream) {
+static SkImageDecoder* sk_libico_dfactory(SkStream* stream) {
     // Check to see if the first four bytes are 0,0,1,0
     // FIXME: Is that required and sufficient?
     SkAutoMalloc autoMal(4);