Yeah I am getting the same thing just about. I downloaded the whole MAME repository last night and then downloaded and applied the mameui173s.rar. Now I get this. Is something still missing?
make: *** No rule to make target '../../../../../src/devices/bus/neogeo/neogeo_slot.cpp', needed by '../../../../mingw-gcc/obj/x64/Release/src/devices/bus/neogeo/neogeo_slot.o'. Stop.
make: *** Waiting for unfinished jobs....
makefile:88: recipe for target 'optional' failed
make: *** [optional] Error 2
makefile:923: recipe for target 'windows_x64' failed
make: *** [windows_x64] Error 2