Add a missing backslash-escape to left brace in a regexp

Perl 5.28 introduced a warning about unescaped left brace in a regexp,
resulting in a warning issued during amavisd startup:

Unescaped left brace in regex is deprecated here (and will be fatal in Perl
5.32), passed through in regex; marked by <-- HERE in m/ ( { <-- HERE }
(?: / \* )? | \* ) / at (eval 112) line 830.

Currently the warning is harmless although annoying, but will become a fatal error
with the next version of perl.

PR:		234173
Submitted by:	Mark.Martinec@ijs.si

security/amavisd-new/Makefile

@@ -2,6 +2,7 @@
 
 PORTNAME=	amavisd-new
 PORTVERSION=	2.11.1
+PORTREVISION=	1
 PORTEPOCH=	1
 CATEGORIES=	security
 MASTER_SITES=	http://www.ijs.si/software/amavisd/ \

security/amavisd-new/files/patch-amavisd

@@ -1,4 +1,4 @@
---- amavisd.orig	2016-12-10 16:31:50 UTC
+--- amavisd.orig	2019-01-14 21:47:08 UTC
 +++ amavisd
 @@ -22814,6 +22814,7 @@ sub process_smtp_request($$$$) {
          }
@@ -8,6 +8,15 @@
  
          $msginfo->client_addr($cl_ip);      # ADDR
          $msginfo->client_port($cl_port);    # PORT
+@@ -28857,7 +28857,7 @@ sub run_av(@) {
+         my $f = $bare_fnames->[$k];  my $multi = 0;
+         if ($one_at_a_time) {  # glob templates may be substrings anywhere
+           local($1);  @query_expanded = @query_template;  # start afresh
+-          s{ ( {} (?: / \* )? | \* ) }
++          s{ ( \{\} (?: / \* )? | \* ) }
+            { $1 eq '{}'   ? "$tempdir/parts"
+            : $1 eq '{}/*' ? ($multi=1,"$tempdir/parts/$f")
+            : $1 eq '*'    ? ($multi=1,$f)  : $1
 @@ -34357,6 +34358,7 @@ sub collect_some_dkim_info($) {
      $sig_ind++;
    }