cmakelists中加入 sdl 的头文件库文件

编译好了sdl库文件，输出到install目录中， 

cmakelists中加入 sdl 的头文件，库文件 

#Require GTK 2.10 or later and Glade
find_package(GTK2 2.10 REQUIRED gtk glade)
#Search for GTK/GTKMM 2.8 or later
#find_package(GTK2 2.8 COMPONENTS gtk gtkmm)
include_directories(${GTK2_INCLUDE_DIRS})

include_directories(${PROJECT_SOURCE_DIR}/install/include)
add_executable(firstsdl gtk_test.c)

link_directories(${PROJECT_SOURCE_DIR}/install/lib)

target_link_libraries(firstsdl libSDL.so ${GTK2_LIBRARIES})