Fix compilation error when building with clang on Linux.

Fix compilation error when building with clang on Linux.

../../src/effects/gradients/SkGradientShader.cpp:487:22: error: unused
function 'bitsTo16' [-Werror,-Wunused-function]
static inline U16CPU bitsTo16(unsigned x, const unsigned bits) {

R=bsalomon@google.com
TEST=make tests

Committed: http://code.google.com/p/skia/source/detail?r=14835

[reed1, 2014-05-21 22:23:48]

lgtm

[commit-bot: I haz the power, 2014-05-21 22:25:06]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/tfarina@chromium.org/287193006/1

[commit-bot: I haz the power, 2014-05-21 22:31:02]

Change committed as 14835

[reed2, 2014-05-22 03:19:34]

A revert of this CL has been created in
https://codereview.chromium.org/297803010/ by reed@chromium.org.

The reason for reverting is: need to revert this along with reverting the big
unitmapper cl.