Fresh ssbs build fails if /sbbs doesn't exist.

Not every user may have a /sbbs directory for some reason or another, especially if it's on a share hosting platform and they don't have root permissions. File locations shouldn't be hard coded to rely on an absolute path.

make[1]: Entering directory '/home/bbs/exec'

BAJA v2.34-Linux (rev 1.52) - Synchronet Shell/Module Compiler

Compiling cntnodes.src... error 2 opening /sbbs/exec/sbbsdefs.inc for read make[1]: *** [GNUmakefile:37: cntnodes.bin] Error 1 make[1]: Leaving directory '/home/bbs/exec' make: *** [GNUmakefile:158: baja] Error 2

The build was obtained by fetching the GNUMakefile and running make in the bbs user's home directory.