Add missing SK_API define.

Add missing SK_API define.

For a detailed explanation of this, please refer to Nico Weber description
here: https://chromiumcodereview.appspot.com/10386108

R=bsalomon@google.com

Committed: https://code.google.com/p/skia/source/detail?r=6489

[tfarina1, 2012-11-19 01:48:49]

Hi Brian, could you review this to me?

Thanks!

[bsalomon, 2012-11-19 13:42:49]

On 2012/11/19 01:48:49, tfarina1 wrote:
> Hi Brian, could you review this to me?
> 
> Thanks!

lgtm

[robertphillips, 2012-11-20 13:34:51]

I reverted this change b.c. it broke the Chrome build. Please see:

http://build.chromium.org/p/tryserver.chromium/builders/win_layout/builds/101...

and

http://build.chromium.org/p/tryserver.chromium/builders/win/builds/37548/step...

Most of the errors I observed revolve around gMapXYProcs; e.g.:

ui.gdi_util.obj : error LNK2001: unresolved external symbol "private: static
void (__cdecl*const * const SkMatrix::gMapXYProcs)(class SkMatrix const
&,float,float,struct SkPoint *)"
(?gMapXYProcs@SkMatrix@@0QBQ6AXABV1@MMPAUSkPoint@@@ZB)

ui.skia_util.obj : error LNK2019: unresolved external symbol "private: static
void (__cdecl*const * const SkMatrix::gMapXYProcs)(class SkMatrix const
&,float,float,struct SkPoint *)"
(?gMapXYProcs@SkMatrix@@0QBQ6AXABV1@MMPAUSkPoint@@@ZB) referenced in function
"public: __thiscall SkFlattenable::SkFlattenable(void)"
(??0SkFlattenable@@QAE@XZ)