[klibc] Makefile: Add dependencies on $(KLIBCKERNELSRC)

The error message for a missing $(KLIBCKERNELSRC) won't appear
unless it's specified as a target or something depends on it.

Make the klcc and klibc targets depend on it.

Link: https://www.zytor.com/pipermail/klibc/2019-January/004030.html
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
1 file changed