make : clean llamafile objects (#8923)

`ggml/src/llamafile/sgemm.o` was not deleted on `make clean`

Author: DrDub

Makefile

@@ -1206,6 +1206,7 @@ clean:
 	rm -rvf ggml/*.dll
 	rm -rvf ggml/*.so
 	rm -vrf ggml/src/*.o
+	rm -rvf ggml/src/llamafile/*.o
 	rm -rvf common/build-info.cpp
 	rm -vrf ggml/src/ggml-metal-embed.metal
 	rm -vrf ggml/src/ggml-cuda/*.o