headers_install: use local file handles

my $unifdef = "scripts/unifdef -U__KERNEL__ -D__EXPORTED_HEADERS__";

foreach my $file (@files) {

	local *INFILE;

	local *OUTFILE;

	my $tmpfile = "$installdir/$file.tmp";

	open(INFILE, "<$readdir/$file")

	open(my $in, '<', "$readdir/$file")

	    or die "$readdir/$file: $!\n";

	open(OUTFILE, ">$tmpfile") or die "$tmpfile: $!\n";

	while (my $line = <INFILE>) {

	open(my $out, '>', $tmpfile)

	    or die "$tmpfile: $!\n";

	while (my $line = <$in>) {

		$line =~ s/([\s(])__user\s/$1/g;

		$line =~ s/([\s(])__force\s/$1/g;

		$line =~ s/([\s(])__iomem\s/$1/g;

		$line =~ s/(^|\s)(inline)\b/$1__$2__/g;

		$line =~ s/(^|\s)(asm)\b(\s|[(]|$)/$1__$2__$3/g;

		$line =~ s/(^|\s|[(])(volatile)\b(\s|[(]|$)/$1__$2__$3/g;

		printf OUTFILE "%s", $line;

		printf {$out} "%s", $line;

	}

	close OUTFILE;

	close INFILE;

	close $out;

	close $in;

	system $unifdef . " $tmpfile > $installdir/$file";

	unlink $tmpfile;

}