glsl/cs: Add gl_WorkGroupID variable

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>

src/glsl/builtin_variables.cpp

@@ -1055,6 +1055,7 @@ builtin_variable_generator::generate_cs_special_vars()
 {
    add_system_value(SYSTEM_VALUE_LOCAL_INVOCATION_ID, uvec3_t,
                     "gl_LocalInvocationID");
+   add_system_value(SYSTEM_VALUE_WORK_GROUP_ID, uvec3_t, "gl_WorkGroupID");
    /* TODO: finish this. */
 }
 

src/glsl/shader_enums.h

@@ -370,6 +370,7 @@ typedef enum
     */
    /*@{*/
    SYSTEM_VALUE_LOCAL_INVOCATION_ID,
+   SYSTEM_VALUE_WORK_GROUP_ID,
    /*@}*/
 
    SYSTEM_VALUE_MAX             /**< Number of values */