glsl: add gl_MaxSamples, new in GL 4.5 / GL ES 3.2

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/compiler/glsl/builtin_variables.cpp

       add_const("gl_MaxTessControlUniformComponents", state->Const.MaxTessControlUniformComponents);
       add_const("gl_MaxTessEvaluationUniformComponents", state->Const.MaxTessEvaluationUniformComponents);
    }
+
+   if (state->is_version(450, 320))
+      add_const("gl_MaxSamples", state->Const.MaxSamples);
 }
 
 

src/compiler/glsl/glsl_parser_extras.cpp

    this->Const.MaxTessControlUniformComponents = ctx->Const.Program[MESA_SHADER_TESS_CTRL].MaxUniformComponents;
    this->Const.MaxTessEvaluationUniformComponents = ctx->Const.Program[MESA_SHADER_TESS_EVAL].MaxUniformComponents;
 
+   /* GL 4.5 / OES_sample_variables */
+   this->Const.MaxSamples = ctx->Const.MaxSamples;
+
    this->current_function = NULL;
    this->toplevel_ir = NULL;
    this->found_return = false;

src/compiler/glsl/glsl_parser_extras.h

       unsigned MaxTessControlTotalOutputComponents;
       unsigned MaxTessControlUniformComponents;
       unsigned MaxTessEvaluationUniformComponents;
+
+      /* GL 4.5 / OES_sample_variables */
+      unsigned MaxSamples;
    } Const;
 
    /**