glsl2: Remove an inlined unvalued return statement.

We already have asserts that it was the last call in the function, so
it's safe to remove after it got cloned in.

Fixes:
glsl-fs-functions-4.

src/glsl/ir_function_inlining.cpp

@@ -97,6 +97,7 @@ replace_return_with_assignment(ir_instruction *ir, void *data)
 	  * have reached here. (see can_inline()).
 	  */
 	 assert(!ret->next->is_tail_sentinal());
+	 ret->remove();
       }
    }
 }