Compile with GCC 7.2.0.

This suppresses the noexcept-type warning, since Skia doesn't have a
stable ABI in any event. GCC now warns on more printf style formats,
so we have to hide our bad test formats a little better. GCC now
also warns on implicit enum to bool conversions, which did catch two
issues.

Change-Id: Ib81769c421757186506873f0fe298ecd0106ae87
Reviewed-on: https://skia-review.googlesource.com/114263
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/example/SkiaSDLExample.cpp b/example/SkiaSDLExample.cpp
index 32c59f3..4314296 100644
--- a/example/SkiaSDLExample.cpp
+++ b/example/SkiaSDLExample.cpp
@@ -208,11 +208,12 @@
     info.fFBOID = (GrGLuint) buffer;
     SkColorType colorType;
 
+    //SkDebugf("%s", SDL_GetPixelFormatName(windowFormat));
+    // TODO: the windowFormat is never any of these?
     if (SDL_PIXELFORMAT_RGBA8888 == windowFormat) {
         info.fFormat = GR_GL_RGBA8;
         colorType = kRGBA_8888_SkColorType;
     } else {
-        SkASSERT(SDL_PIXELFORMAT_BGRA8888);
         colorType = kBGRA_8888_SkColorType;
         if (SDL_GL_CONTEXT_PROFILE_ES == contextType) {
             info.fFormat = GR_GL_BGRA8;