mesa/glsl: remove unused uses_builtin_functions field

This has been unused since 943b69cddd

Reviewed-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>

src/compiler/glsl/glsl_parser_extras.cpp

@@ -1984,7 +1984,6 @@ _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader,
    shader->InfoLog = state->info_log;
    shader->Version = state->language_version;
    shader->IsES = state->es_shader;
-   shader->info.uses_builtin_functions = state->uses_builtin_functions;
 
    /* Retain any live IR, but trash the rest. */
    reparent_ir(shader->ir, shader->ir);

src/mesa/main/ff_fragment_shader.cpp

@@ -1258,7 +1258,6 @@ create_new_program(struct gl_context *ctx, struct state_key *key)
 
    p.shader->CompileStatus = true;
    p.shader->Version = state->language_version;
-   p.shader->info.uses_builtin_functions = state->uses_builtin_functions;
    p.shader_program->Shaders =
       (gl_shader **)malloc(sizeof(*p.shader_program->Shaders));
    p.shader_program->Shaders[0] = p.shader;

src/mesa/main/mtypes.h

@@ -2172,7 +2172,6 @@ struct gl_subroutine_function
  */
 struct gl_shader_info
 {
-   bool uses_builtin_functions;
    bool uses_gl_fragcoord;
    bool redeclares_gl_fragcoord;
    bool ARB_fragment_coord_conventions_enable;