ANGLE: Stop using unsafe strcpy method

ANGLE: Stop using unsafe strcpy method
<http://webkit.org/b/129237>
<rdar://problem/11077580>

Reviewed by Dean Jackson.

* include/GLSLANG/ShaderLang.h:
- Drive-by fix for header documentation.

* src/compiler/translator/ShaderLang.cpp:
(ShGetInfoLog):
(ShGetObjectCode):
* src/libGLESv2/Program.cpp:
(gl::InfoLog::append):
- Switch to use strncpy(), and explicitly set NULL terminator at
  the end of the buffer.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@164580 268f45cc-cd09-0410-ab3c-d52691b4dbfc