Upstream:
https://dev.gnupg.org/rE4615816f71e91f4c3bb8b0e4122dd153ec7c1927
https://dev.gnupg.org/T6136

From 4615816f71e91f4c3bb8b0e4122dd153ec7c1927 Mon Sep 17 00:00:00 2001
From: NIIBE Yutaka <gniibe@fsij.org>
Date: Thu, 25 Aug 2022 15:30:07 +0900
Subject: [PATCH] gpgrt-config: Strip system paths for --cflags and --libs.

* src/gpgrt-config.in: Strip -I and -L with system paths.

--

This behavior is more compatible to pkg-config.

GnuPG-bug-id: 6136
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

diff --git a/src/gpgrt-config.in b/src/gpgrt-config.in
index 3aaa243..85d21b4 100644
--- a/src/gpgrt-config.in
+++ b/src/gpgrt-config.in
@@ -1,6 +1,6 @@
 #!@INSTALLSHELLPATH@
 #                          -*- mode: shell-script; sh-shell: "/bin/sh" -*-
-# Copyright (C) 2018, 2021 g10 Code GmbH
+# Copyright (C) 2018, 2021, 2022 g10 Code GmbH
 #
 # This file is free software; as a special exception the author gives
 # unlimited permission to copy and/or distribute it, with or without
@@ -193,9 +193,14 @@ list_only_once () {
     __arg=""
 
     for __arg; do
-	if not_listed_yet $__arg $__result; then
-	    __result="$__result${__result:+ }$__arg"
-	fi
+	case "$__arg" in
+	    -I/usr/include|-I/include) ;;
+	    *)
+                if not_listed_yet $__arg $__result; then
+	            __result="$__result${__result:+ }$__arg"
+	        fi
+                ;;
+	esac
     done
 
     echo $__result
@@ -210,6 +215,7 @@ list_only_once_for_libs () {
     # the resulted list is in reverse order
     for __arg; do
 	case "$__arg" in
+	    -L/usr/lib|-L/usr/lib64|-L/lib|-L/lib64) ;;
 	    -l*)
 		# As-is
 		__rev_list="$__arg${__rev_list:+ }$__rev_list"