net-misc/linuxptp: fix implicit function declaration for strncpy

Unlike normal missing includes, implicit function declaration
fixes require a revbump as they can affect code generation.

Observed on musl.

Signed-off-by: Sam James <sam@gentoo.org>

net-misc/linuxptp/files/linuxptp-3.1.1-string-include.patch

@@ -0,0 +1,21 @@
+https://cgit.openembedded.org/meta-openembedded/commit/?h=master-next&id=aec96f23775b946cf99c39e7274bcc8fdd4711ca
+https://sourceforge.net/p/linuxptp/mailman/message/37603438/
+
+From d49b4fb8063ecd89617587e5ea566cc9da9393ef Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Wed, 31 Aug 2022 19:09:18 -0700
+Subject: [PATCH] include string.h for strncpy()
+
+Upstream-Status: Pending
+
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+--- a/interface.c
++++ b/interface.c
+@@ -5,6 +5,7 @@
+  * @note SPDX-License-Identifier: GPL-2.0+
+  */
+ #include <stdlib.h>
++#include <string.h>
+ #include "interface.h"
+ 
+ struct interface {

net-misc/linuxptp/linuxptp-3.1.1-r1.ebuild

@@ -19,6 +19,7 @@ CONFIG_CHECK="~NETWORK_PHY_TIMESTAMPING ~PPS ~PTP_1588_CLOCK"
 
 PATCHES=(
 	"${FILESDIR}"/${PN}-3.1.1-user_cpp.patch
+	"${FILESDIR}"/${PN}-3.1.1-string-include.patch
 )
 
 pkg_setup() {