FindSDL_net

尋找 SDL_net 函式庫

此模組定義：

SDL_NET_LIBRARIES, the name of the library to link against
SDL_NET_INCLUDE_DIRS, where to find the headers
SDL_NET_FOUND, if false, do not try to link against
SDL_NET_VERSION_STRING - human-readable string containing the version of SDL_net

為了向後相容，也會設定以下變數：

SDLNET_LIBRARY (same value as SDL_NET_LIBRARIES)
SDLNET_INCLUDE_DIR (same value as SDL_NET_INCLUDE_DIRS)
SDLNET_FOUND (same value as SDL_NET_FOUND)

$SDLDIR 是一個環境變數，對應於建置 SDL 時使用的 ./configure --prefix=$SDLDIR。