glcpp: Automatically #define GL_core_profile 1 on GLSL 1.50+.
glcpp: Automatically #define GL_core_profile 1 on GLSL 1.50+.

Page 17 of the GLSL 1.50.11 specification states:
"There is a built-in macro definition for each profile the
 implementation supports.  All implementations provide the following
 macro:

Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>
Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>

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