Enhance Makefile to use implicit rule and extends CFLAGS instead of setting it if it doesn't exists
Enhance Makefile to use implicit rule and extends CFLAGS instead of setting it if it doesn't exists

mevdschee/2048.c,mevdschee/2048.c,byannoni/2048.c,byannoni/2048.c,lvfeng1130/2048.c,lvfeng1130/2048.c