Ports: Update flex's patches to use git patches

Ports/flex/patches/0003-Replace-libc-s-regex-includes-with-pcre2.patch

@@ -0,0 +1,25 @@
+From 2aecd57dbc3eb793db2996807f4c17e0c5880d75 Mon Sep 17 00:00:00 2001
+From: Brian Callahan <bcallah@openbsd.org>
+Date: Thu, 23 Jan 2020 23:43:31 -0500
+Subject: [PATCH 3/6] Replace libc's regex includes with pcre2
+
+---
+ src/flexdef.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/flexdef.h b/src/flexdef.h
+index 9dac654..2bdf9fb 100644
+--- a/src/flexdef.h
++++ b/src/flexdef.h
+@@ -72,7 +72,7 @@
+ #include <stdbool.h>
+ #include <stdarg.h>
+ /* Required: regcomp(), regexec() and regerror() in <regex.h> */
+-#include <regex.h>
++#include <pcre2posix.h>
+ /* Required: strcasecmp() in <strings.h> */
+ #include <strings.h>
+ #include "flexint.h"
+-- 
+2.36.1
+