Fixed world breakage due to missing include of <sys/cdefs.h> in previous
commit.

Fixed related style bugs:
basename.c: misplaced '#if 0'
dirname.c: misplaced '#if 0'
getgrent.c: missing '#if 0', and tab lossage in vendor id (the previous

            commit fixed the complete corruption of the vendor id but
	    lost a tab)

getpwent.c: missing '#if 0'