ssw is a library containing simple wrappers for basic X11 functions (/stdlib functions) included from 'X11/Xutil.h' (and stdlib.h)
(g)cc -c -fpic ssw.c -o ssw.o -lX11
(g)cc -c -shared ssw.o -o libssw.so -lX11
then, as root:
cp libssw.so /usr/lib/
cp ssw.h /usr/include/