crt1.o: provide symbol definition of __progname

crt1.o: provide symbol definition of __progname

When the linker version script requests "local: *", the linker chokes on
it because the weak __progname crt1.o symbol comes back undefined.

This is a duplicate definition to the ones provided by csu, but harmless
since the linker resolves it.

Also cleaned up some files involving libc_private.h that should have been
updated in previous changesets.