compute min target based on host version of MACOSX instead of version of available SDK

configs/config-desktop.cmake

@@ -51,6 +51,11 @@ set(DEFAULT_VALUE_CMAKE_LINKING_TYPE "-DENABLE_STATIC=NO")
 # Global configuration
 set(LINPHONE_BUILDER_HOST "")
 if(APPLE)
+	#if (NOT CMAKE_OSX_DEPLOYMENT_TARGET) #is it still usefull ?
+		#without instruction chose to target current machine
+	#	execute_process(COMMAND sw_vers -productVersion  COMMAND awk -F \\. "{printf \"%i.%i\",$1,$2}"  RESULT_VARIABLE xcrun_sdk_version OUTPUT_VARIABLE CMAKE_OSX_DEPLOYMENT_TARGET OUTPUT_STRIP_TRAILING_WHITESPACE)
+	#endif()
+
 	if(CMAKE_SIZEOF_VOID_P EQUAL 8)
 		set(CMAKE_OSX_ARCHITECTURES "x86_64")
 		set(LINPHONE_BUILDER_HOST "x86_64-apple-darwin")