mesa/glsl: rename preprocess to glcpp_preprocess

This symbol with dricore escapes into the namespace, its too generic,
we should prefix it with something just to be nice.

Should be applied to stable + 9.0

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/mesa/program/ir_to_mesa.cpp

@@ -3060,7 +3060,7 @@ _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader)
       return;
    }
 
-   state->error = preprocess(state, &source, &state->info_log,
+   state->error = glcpp_preprocess(state, &source, &state->info_log,
 			     &ctx->Extensions, ctx->API);
 
    if (ctx->Shader.Flags & GLSL_DUMP) {