Use updated Khronos signature for glShaderSource

Use updated Khronos signature for glShaderSource
(const char* const instead of char**).

This is needed for new Khronos headers.

BUG=178589
Committed: http://code.google.com/p/skia/source/detail?r=7900

[Paweł Hajdan Jr., 2013-02-27 00:36:38]

If you want to add more people to review, please do so directly (do not wait for
me to do that). Thanks!

[bsalomon, 2013-02-27 19:20:30]

On 2013/02/27 00:36:38, Paweł Hajdan Jr. wrote:
> If you want to add more people to review, please do so directly (do not wait
for
> me to do that). Thanks!

lgtm

[commit-bot: I haz the power, 2013-02-27 19:20:53]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/phajdan.jr@chromium.org/12310156/1

[commit-bot: I haz the power, 2013-02-27 19:20:55]

Presubmit check for 12310156-1 failed and returned exit status 1.

INFO:root:Found 1 file(s).
Running presubmit commit checks ...
Running /b/commit-queue/workdir/skia/PRESUBMIT.py

** Presubmit Warnings **
Tree state is: caution

***************
Tree is caution : junov committing change that affects DEPS roll - RP will
rebaseline ANGLE images
http://skia-tree-status.appspot.com/banner-status?format=json
***************

[commit-bot: I haz the power, 2013-02-28 17:11:07]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/phajdan.jr@chromium.org/12310156/1

[commit-bot: I haz the power, 2013-02-28 17:11:12]

Change committed as 7900