Fix build on OSX: Export missing sys.cstring function

Fix NetBSD build.

Don't specify .comm alignment.

	It seems to confuse lld.

Allow 'make release' to override version.

Missing an FD.

Fix final warnigns on OSX builds.

	The OSX deployment target should also be set for building
	rt/_myrrt.o

Fix final warnigns on OSX builds.

	The OSX deployment target should also be set for building
	rt/_myrrt.o