cmp: remove -? (#567)

* Non-standard -? option doesn't exist in BSD versions of cmp either
* For systems with no perldoc command installed, we have a bin/perldoc, so running "perl perldoc cmp" is preferred (i.e. the same way to show a manual for maze and other programs too)

bin/cmp

@@ -70,8 +70,7 @@ my $lines_read = 0;
 my $saw_difference;
 
 my %opt;
-getopts('?ls', \%opt) or usage();
-manual() if $opt{'?'};
+getopts('ls', \%opt) or usage();
 if ($opt{'l'}) {
     if ($opt{'s'}) {
         warn "$Program: options -l and -s are incompatible\n";
@@ -231,15 +230,6 @@ sub usage {
     exit EX_USAGE;
 }
 
-sub manual {
-	require Pod::Usage;
-
-	Pod::Usage::pod2usage({
-		-exitval => EX_SUCCESS,
-		-verbose => 2,
-	});
-}
-
 __END__
 
 =head1 NAME
@@ -290,10 +280,6 @@ list differences; return the byte number and the differing byte values
 for each difference between the two files.  The byte number is given
 in decimal, and the byte values are given in octal.
 
-=item -?
-
-show the documentation
-
 =back
 
 =head1 ENVIRONMENT