For graphics/MesaLib the build failed because of the missing sys/shm.h file.

Here is the patch for src/mesa/drivers/x11/glxheader.h:

 # ifdef USE_XSHM  /* was SHM */
 #  include <sys/ipc.h>
+#ifndef __QNXNTO__
 #  include <sys/shm.h>
+#endif
 #  include <X11/extensions/XShm.h>
 # endif

and it worked - therefore the required functions are available in QNX. I do not which function prototypes for shared 
memory operation are belonging to shm.h.