Make usage strings dash-less

When you misuse a git command, you are shown the usage string.
But this is currently shown in the dashed form.  So if you just
copy what you see, it will not work, when the dashed form
is no longer supported.

This patch makes git commands show the dash-less version.

For shell scripts that do not specify OPTIONS_SPEC, git-sh-setup.sh
generates a dash-less usage string now.

Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/git-cvsimport.perl b/git-cvsimport.perl
index cacbfc0..e2664ef 100755
--- a/git-cvsimport.perl
+++ b/git-cvsimport.perl
@@ -36,7 +36,7 @@
 	my $msg = shift;
 	print(STDERR "Error: $msg\n") if $msg;
 	print STDERR <<END;
-Usage: ${\basename $0}     # fetch/update GIT from CVS
+Usage: git cvsimport     # fetch/update GIT from CVS
        [-o branch-for-HEAD] [-h] [-v] [-d CVSROOT] [-A author-conv-file]
        [-p opts-for-cvsps] [-P file] [-C GIT_repository] [-z fuzz] [-i] [-k]
        [-u] [-s subst] [-a] [-m] [-M regex] [-S regex] [-L commitlimit]