glShaderSource must not change compile status.

glShaderSource must not change compile status.

OpenGL 4.5 Core Profile section 7.1, in the documentation for
CompileShader, says: "Changing the source code of a shader object with
ShaderSource does not change its compile status or the compiled shader
code."

According to Karol Herbst, the game "Divinity: Original Sin - Enhanced
Edition" depends on this odd quirk of the spec.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93551
Signed-off-by: Jamey Sharp <jamey@minilop.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>