fix failed assertion (parameter can be a PROGRAM_CONSTANT)
diff --git a/src/mesa/shader/prog_execute.c b/src/mesa/shader/prog_execute.c
index 00a3750..7f9687c 100644
--- a/src/mesa/shader/prog_execute.c
+++ b/src/mesa/shader/prog_execute.c
@@ -89,6 +89,7 @@
       else {
          const struct gl_program_parameter_list *params;
          ASSERT(source->File == PROGRAM_LOCAL_PARAM ||
+                source->File == PROGRAM_CONSTANT ||
                 source->File == PROGRAM_STATE_VAR);
          params = machine->CurProgram->Parameters;
          if (reg < 0 || reg >= params->NumParameters)