Git.pm: allow command_close_bidi_pipe to be called as method

The documentation of command_close_bidi_pipe() claims that it can
be called as a method, but it does not check whether the first
argument is $self or not assuming the latter.  Using _maybe_self()
fixes this.

Signed-off-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: mina86

perl/Git.pm

@@ -430,7 +430,7 @@ have more complicated structure.
 
 sub command_close_bidi_pipe {
 	local $?;
-	my ($pid, $in, $out, $ctx) = @_;
+	my ($self, $pid, $in, $out, $ctx) = _maybe_self(@_);
 	foreach my $fh ($in, $out) {
 		unless (close $fh) {
 			if ($!) {