dselect: Use a matching group instead of ${^MATCH} in s///

It seems that this is not supported or does not work in perl 5.14.0,
although it should be since 5.10.0. Switch to a group matching to
allow using older perl version from stable.

debian/changelog

@@ -1,5 +1,8 @@
 dpkg (1.17.23) UNRELEASED; urgency=low
 
+  [ Guillem Jover ]
+  * Use a matching group instead of ${^MATCH} in s/// in dselect build script.
+
   [ Updated programs translations ]
   * Basque (Iñaki Larrañaga Murgoitio). Closes: #771893
   * Catalan (Guillem Jover).

dselect/mkcurkeys.pl

@@ -140,6 +140,6 @@ sub capit {
 sub p {
     my ($k, $v) = @_;
 
-    $v =~ s/["\\]/\\${^MATCH}/pg;
+    $v =~ s/(["\\])/\\$1/g;
     printf("  { %-15s \"%-20s },\n", $k . ',', $v . '"') or die $!;
 }