Bug#764152: assaultcube: update config.{sub, guess} to support new architectures

[Wookey]

Package: assaultcube
Followup-For: Bug #764152

Aurels' patch really ought to fix this problem, but in fact does not,
because the packages runs configure in the clean target, and this
happens before the config.sub/guess have been updated. The problem is
the same whether autoreconf or autotools-dev is used.

The problem seems to be this set of rules in src/Makefile (which is a
static makefiles, not generated by automake)

../enet/Makefile:
	cd ../enet; ./configure --enable-shared=no --enable-static=yes

clean-enet: ../enet/Makefile
	$(MAKE) -C ../enet/ distclean

clean:  clean-enet
	-$(RM) $(CLIENT_PCH) $(CLIENT_OBJS) $(SERVER_OBJS) $(MASTER_OBJS) ac_client$
#       -$(MAKE) -C ../enet/ clean

which runs configure even on clean

This logic needs correcting.