Improve CMake find modules.

This adds the possibility for Tox modules like AV to be optional.

CMakeLists.txt

@@ -22,8 +22,11 @@ cmake_minimum_required(VERSION 2.8.7)
 project(tox-weechat C)
 
 set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake ${CMAKE_MODULE_PATH})
-find_package(WeeChat)
-find_package(Tox)
+
+find_package(WeeChat REQUIRED)
+find_package(Tox REQUIRED
+    COMPONENTS CORE
+    OPTIONAL_COMPONENTS AV)
 
 set(PLUGIN_PATH "lib/weechat/plugins" CACHE PATH
     "Path to install the plugin binary to.")
@@ -48,11 +51,14 @@ add_library(tox MODULE
 set(CMAKE_C_FLAGS_DEBUG "-DTWC_DEBUG")
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu99 -Wall -Wextra -Wno-unused-parameter")
 
-include_directories(${TOX_INCLUDE_DIR})
-include_directories(${WEECHAT_INCLUDE_DIR})
+include_directories(${Tox_INCLUDE_DIRS})
+include_directories(${WeeChat_INCLUDE_DIRS})
 
-target_link_libraries(tox ${TOX_LIBRARY})
-target_link_libraries(tox ${TOXAV_LIBRARY})
+target_link_libraries(tox ${Tox_LIBRARIES})
+
+if(Tox_AV_FOUND)
+    add_definitions(-DTOXAV_ENABLED)
+endif()
 
 # remove lib prefix (libtox.so -> tox.so)
 set_target_properties(tox PROPERTIES PREFIX "")