Rename all __gl_ functions to Sk__gl_ to avoid conflicting with other copies

Rename all __gl_ functions to Sk__gl_ to avoid conflicting with other copies
of libtess that might be statically linked by Skia clients (done via gluos.h, rather that touching source directly).

Specfically, this is required to enable incremental linking on Windows builds
of Chromium because WebKit has a copy of libtess also.

Previously http://codereview.appspot.com/4536080/ and http://trac.webkit.org/changeset/87178 but go a bit farther because the internal __gl_ functions collide with incremental linking because .objs are linked directly, rather than via .lib

http://code.google.com/p/chromium/issues/detail?id=92172
http://code.google.com/p/skia/issues/detail?id=338

[Stephen White, 2011-08-10 13:55:11]

Medium-term, we plan to remove the copy of libtess in WebKit, which should
eliminate the need for all this renaming.

But this LGTM for now.

[scottmg, 2011-08-10 14:24:39]

On 2011/08/10 13:55:11, Stephen White wrote:
> Medium-term, we plan to remove the copy of libtess in WebKit, which should
> eliminate the need for all this renaming.
> 
> But this LGTM for now.

OK, thanks. Would you mind doing the commit? (assuming no one else objects to
the change)

[Stephen White, 2011-08-10 17:49:58]

On 2011/08/10 14:24:39, scottmg wrote:
> On 2011/08/10 13:55:11, Stephen White wrote:
> > Medium-term, we plan to remove the copy of libtess in WebKit, which should
> > eliminate the need for all this renaming.
> > 
> > But this LGTM for now.
> 
> OK, thanks. Would you mind doing the commit? (assuming no one else objects to
> the change)

Landed as r2095.  Closing.