Fix gyp files to allow ninja to build 64 bit on Mac.

Fix gyp files to allow ninja to build 64 bit on Mac.
Fix warnings that cropped up building as 64-bit.

BUG=

Committed: http://code.google.com/p/skia/source/detail?r=8814

[mtklein, 2013-04-18 22:17:35]

Ben and I weren't sure what was going on with the (size_t) casts in those
asserts.  Building in 64-bit mode brought up a warning that basically said
"Warning: your assertion is always true."

[mtklein, 2013-04-19 13:53:23]

On 2013/04/18 22:17:35, mtklein wrote:
> Ben and I weren't sure what was going on with the (size_t) casts in those
> asserts.  Building in 64-bit mode brought up a warning that basically said
> "Warning: your assertion is always true."

Mike filled me in on this, which was to do compile-time asserts.  I switched
them over to use the appropriate STATIC or COMPILE assert.

[bungeman-skia, 2013-04-19 14:05:13]

The gypi change and cast in the .m lgtm. I'll leave the asserts to reed or
bsalomon.

[bsalomon, 2013-04-19 14:36:01]

On 2013/04/19 14:05:13, bungeman1 wrote:
> The gypi change and cast in the .m lgtm. I'll leave the asserts to reed or
> bsalomon.

lgtm

[commit-bot: I haz the power, 2013-04-19 19:14:56]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/mtklein@google.com/13852013/3001

[commit-bot: I haz the power, 2013-04-19 19:28:40]

Retried try job too often on Skia_MacMiniLion_Float_Compile_Release_32_Trybot
for step(s) BuildBench, BuildMost
http://108.170.217.252:10117/buildstatus?builder=Skia_MacMiniLion_Float_Compi...

[commit-bot: I haz the power, 2013-04-22 17:45:30]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/mtklein@google.com/13852013/13001

[commit-bot: I haz the power, 2013-04-22 20:26:47]

Change committed as 8814