Msys2 Makefile.meson: Add client/ruledit to build dir name
Add 'client' or 'ruledit' part to the name of Makefile.meson build directory. That makes, e.g., 'make clean' to work better as "*-$(GUI)" does not match both client and ruledit by the same gui.
Add 'client' or 'ruledit' part to the name of Makefile.meson build directory. That makes, e.g., 'make clean' to work better as "*-$(GUI)" does not match both client and ruledit by the same gui.