package/mbpoll: fix build without c++

Add patch to enable build without c++.

Add configure option to fix subsequent configure error due to patched
source file during git version check:

CMake Error at cmake/GitVersion.cmake:118 (message):
  Unable to find current project version !
Call Stack (most recent call first):
  CMakeLists.txt:100 (GetGitVersion)

Fixes:
http://autobuild.buildroot.net/results/2f8/2f819871a89cb2a2df239b1f879c1babcdd022fc/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/mbpoll/0001-CMakeLists.txt-Add-LANGUAGES-option-to-project-varia.patch

@@ -0,0 +1,30 @@
+From 97a2c39fea591509ac1f8a31598b7555b63b8d55 Mon Sep 17 00:00:00 2001
+From: Bernd Kuhls <bernd@kuhls.net>
+Date: Sun, 30 Jul 2023 08:45:58 +0200
+Subject: [PATCH] CMakeLists.txt: Add LANGUAGES option to project variable
+
+Fixes build with toolchains without c++.
+
+Upstream: https://github.com/epsilonrt/mbpoll/pull/71
+
+Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
+---
+ CMakeLists.txt | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 6daa039..11dcd05 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -3,7 +3,7 @@
+ cmake_minimum_required(VERSION 2.9)
+ 
+ # Workspace name
+-project(mbpoll)
++project(mbpoll LANGUAGES C)
+ 
+ # This setting is useful for providing JSON file used by CodeLite for code completion
+ set(CMAKE_EXPORT_COMPILE_COMMANDS 1)
+-- 
+2.39.2
+

package/mbpoll/mbpoll.mk

@@ -9,5 +9,6 @@ MBPOLL_SITE = $(call github,epsilonrt,mbpoll,v$(MBPOLL_VERSION))
 MBPOLL_DEPENDENCIES = host-pkgconf libmodbus
 MBPOLL_LICENSE = GPL-3.0+
 MBPOLL_LICENSE_FILES = COPYING
+MBPOLL_CONF_OPTS = -DGIT_EXECUTABLE=/bin/false
 
 $(eval $(cmake-package))