Fix SDL2 directfb includes under Alpine Linux

Source/Tools/FEXConfig/CMakeLists.txt

@@ -12,6 +12,9 @@ add_executable(${NAME} ${SRCS})
 target_include_directories(${NAME} PRIVATE ${CMAKE_SOURCE_DIR}/Source/)
 target_include_directories(${NAME} PRIVATE ${CMAKE_SOURCE_DIR}/External/imgui/examples/)
 
+# Fix for SDL2 includes under Alpine Linux.
+target_include_directories(${NAME} PRIVATE /usr/include/directfb/)
+
 if (TARGET SDL2::SDL2)
   target_link_libraries(${NAME} PRIVATE SDL2::SDL2)
 else()