$ make -f client.mk build
/usr/bin/make -f /mozilla/client.mk build
make[1]: Entering directory `/c/cygwin/mozilla'
make[1]: /mozilla/client.mk: No such file or directory
make[1]: *** No rule to make target `/mozilla/client.mk'.  Stop.
make[1]: Leaving directory `/c/cygwin/mozilla'
make: *** [build] Error 2