* Makefile.in (VER): Change "head -1" to "sed q", since POSIX
1003.1-2001 no longer allows "head -1".
* gdb/Makefile.in (version.c): Likewise.
* gdb/doc/Makefile.in (GDBvn.texi): Likewise.
* gdb/CONTRIBUTE: Change "diff -c3" to "diff -c", which is
equivalent.  POSIX 1003.1-2001 no longer allows "diff -c3".