i am trying the compile of a example for the library directFB and other for library cairo. I have isntall the libraries directFB and Cairo.

The first step: i create a new package type "src-make-prog".

2: copy the example "hello world" in the new file "helloworld*.c"

3: I modify the Makefile file  and i  add:

CFLAGS   = -g -Wall -O2 -MD `pkg-config --cflags directfb`

LDFLAGS  = -g -Wall -O2 `pkg-config --libs directfb`

for cairo is the same but the flags are:

CFLAGS   = -g -Wall -O2 -MD `pkg-config --cflags cairo`

LDFLAGS  = -g -Wall -O2 `pkg-config --libs cairo`

In both cases, the compiler say me: 

undefined reference to `DirectFBInit', etc...

undefined reference to `cairo_image_surface_create',etc...

Am I doing it the right way or I need something more to add?