Added $Id$ to Makefile, updated strip.1 and strip.c to lattest from NetBSD,

Added $Id$ to Makefile, updated strip.1 and strip.c to lattest from NetBSD,
with special support for -x option.

These are the applicable excerpts from the NetBSD rlog:
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revision 1.6
date: 1993/09/07 16:12:15;  author: brezak;  state: Exp;  lines: +2 -1
Remove filenames with -x flag, too.
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revision 1.5
date: 1993/08/27 02:33:36;  author: brezak;  state: Exp;  lines: +14 -2
Add -x flag to remove stabs, compiler idents and local symbols.
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