Fix potential SEGV on long header when verify = header_syntax is used

this is not set not in the default configuration, check with
  grep 'verify.*=.*header_syntax' /usr/local/etc/exim/configure

  <http://www.guninski.com/exim1.html>

mail/exim/Makefile

@@ -7,7 +7,7 @@
 
 PORTNAME=	exim
 PORTVERSION=	${EXIM_VERSION}+${EXISCAN_VERSION}
-PORTREVISION=	0
+PORTREVISION=	1
 CATEGORIES=	mail
 MASTER_SITES=	${MASTER_SITE_EXIM}
 MASTER_SITE_SUBDIR=	exim4

mail/exim/files/patch-src::verify.c

@@ -0,0 +1,22 @@
+#
+# Fix SEGV on long headers when verify = header_syntax is used
+#  <http://www.guninski.com/exim1.html>
+#
+--- src/verify.c.orig	Thu May  6 15:46:44 2004
++++ src/verify.c	Thu May  6 15:47:27 2004
+@@ -1264,14 +1264,9 @@
+ 
+     if (recipient == NULL && Ustrcmp(errmess, "empty address") != 0)
+       {
+-      uschar hname[64];
+-      uschar *t = h->text;
+-      uschar *tt = hname;
++      uschar *t;
+       uschar *verb = US"is";
+       int len;
+-
+-      while (*t != ':') *tt++ = *t++;
+-      *tt = 0;
+ 
+       /* Arrange not to include any white space at the end in the
+       error message. */