Don't enforce C++11 standard

The default in Ubuntu 18.04 and 20.04 is C++14.
Ubuntu 22.04 uses C++17 as the gcc default, which is required by log4cxx there.

realsense2_camera/CMakeLists.txt

@@ -1,6 +1,5 @@
 cmake_minimum_required(VERSION 2.8.3)
 project(realsense2_camera)
-add_compile_options(-std=c++11)
 
 option(BUILD_WITH_OPENMP "Use OpenMP" OFF)
 option(SET_USER_BREAK_AT_STARTUP "Set user wait point in startup (for debug)" OFF)
@@ -62,7 +61,7 @@ endif()
 
 if (WIN32)
 else()
-set(CMAKE_CXX_FLAGS "-fPIE -fPIC -std=c++11 -D_FORTIFY_SOURCE=2 -fstack-protector -Wformat -Wformat-security -Wall ${CMAKE_CXX_FLAGS}")
+set(CMAKE_CXX_FLAGS "-fPIE -fPIC -D_FORTIFY_SOURCE=2 -fstack-protector -Wformat -Wformat-security -Wall ${CMAKE_CXX_FLAGS}")
 endif()
 
 add_message_files(