checkincludes.pl: provide usage helper

# checkincludes: Find files included more than once in (other) files.

# Copyright abandoned, 2000, Niels Kristian Bech Jensen <nkbj@image.dk>.

sub usage {

	print "Usage: checkincludes.pl <file list>\n";

	exit 1;

}

if ($#ARGV < 0) {

        usage();

}

foreach $file (@ARGV) {

	open(FILE, $file) or die "Cannot open $file: $!.\n";