Ports: Update mandoc's patches to use git patches

Ports/mandoc/patches/0004-Use-pcre2-for-regex.patch

@@ -0,0 +1,25 @@
+From 173fe2329bb943dba5e0c85c16403e0a4ee61b2f Mon Sep 17 00:00:00 2001
+From: Brian Callahan <bcallah@openbsd.org>
+Date: Sat, 25 Jan 2020 21:20:39 -0500
+Subject: [PATCH 4/9] Use pcre2 for regex
+
+---
+ dba_read.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/dba_read.c b/dba_read.c
+index e976057..6183dcb 100644
+--- a/dba_read.c
++++ b/dba_read.c
+@@ -19,7 +19,7 @@
+  * The interface is defined in "dba.h".
+  * This file is seperate from dba.c because this also uses "dbm.h".
+  */
+-#include <regex.h>
++#include <pcre2posix.h>
+ #include <stdint.h>
+ #include <stdlib.h>
+ #include <stdio.h>
+-- 
+2.36.1
+