Makefile: some rework with better dependency tracking
Makefile: some rework with better dependency tracking

More to come later

iamyuiwong/dlfcn-win32,dlfcn-win32/dlfcn-win32,dlfcn-win32/dlfcn-win32,gypified/dlfcn-win32,gypified/dlfcn-win32