to NetBSD 6.1)
introduce compat61 (and compat61-x11 with it) as a backward compatibility
package to NetBSD 7
add compat61* to mk/emulator/netbsd-compat.mk and emulators/Makefile
some sort of version for the binary compat packages might have been
useful, maybe abusing the DIST_SUBDIR? compat61 is likely to change
if/when NetBSD 6.2 is released
