scripts/get_maintainer.pl: Print proper error message for missing $file

If you pass scripts/get_maintainer.pl the name of a FIFO or other
exciting object (/dev/stdin, for example), it would falsely print
"file not found".  Instead: stat the object rather than using -f so
that we do not mind if the object is not a file; and print the errno
value in the error message.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Thomas Huth <thuth@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <1520535787-6223-13-git-send-email-ian.jackson@eu.citrix.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

scripts/get_maintainer.pl

@@ -381,8 +381,8 @@ foreach my $file (@ARGV) {
 	##if $file is a directory and it lacks a trailing slash, add one
 	if ((-d $file)) {
 	    $file =~ s@([^/])$@$1/@;
-	} elsif (!(-f $file)) {
-	    die "$P: file '${file}' not found\n";
+	} elsif (!(stat $file)) {
+	    die "$P: file '${file}' not found: $!\n";
 	}
     }
     if ($from_filename) {