Log Message:
fix compat60 (and strip down a lot to a backward compatibility package
	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