Make Unicode script fit for future versions

Between Unicode 15.0.0 and 15.1.0, the whitespace in
EastAsianWidth.txt has changed a bit, such as from

0020;Na          # Zs         SPACE

to

0020           ; Na # Zs         SPACE

with space around the semicolon.  Adjust the script to be able to
parse that.

src/common/unicode/generate-unicode_east_asian_fw_table.pl

@@ -23,7 +23,7 @@ foreach my $line (<ARGV>)
 	chomp $line;
 	$line =~ s/\s*#.*$//;
 	next if $line eq '';
-	my ($codepoint, $width) = split ';', $line;
+	my ($codepoint, $width) = split /\s*;\s*/, $line;
 
 	if ($codepoint =~ /\.\./)
 	{