Each BSP contains the binary and the source code for the appropriate flash filesystem driver, but the QNX Neutrino RTOS contains the associated header files and libraries.
Typing make in the bsp_working_dir generates the flash filesystem binary. Normally, you won't need to remake the flash filesystem driver unless you've changed the size or configuration of the flash on the board — this can include the number of parts, size of parts, type of parts, interleave, etc.