Add option to enable video when compiling using cmake.

CMakeLists.txt

@@ -1,6 +1,8 @@
 cmake_minimum_required(VERSION 2.6)
 project(LINPHONE C)
 
+option(LINPHONE_ENABLE_VIDEO "Build linphone with video support." ON)
+
 if(NOT ORTP_ROOT_DIR)
 	set(ORTP_ROOT_DIR ${CMAKE_CURRENT_SOURCE_DIR}/oRTP)
 endif()

coreapi/CMakeLists.txt

@@ -98,6 +98,10 @@ add_definitions(
 	-DLINPHONE_PLUGINS_DIR=""
 )
 
+if(LINPHONE_ENABLE_VIDEO)
+	add_definitions(-DVIDEO_ENABLED)
+endif(LINPHONE_ENABLE_VIDEO)
+
 if(WIN32)
 add_definitions(
 	-DWINDOW_NATIVE