audio/gsm: update to 1.0.22

Major changes

• Use $(RMFLAGS) with the rms in the Makefile.
• add -f to $(RMFLAGS) to avoid spurious error messages during build
• Use $(LN), not ln, in the Makefile rules for the installed binary of untoast and tcat.
• Remove unused, and occasionally out of date, VERSION variable from Makefile.

Port changes:

• Remove openwrt MASTER_SITE, no distfile available anymore