INT 21 - Novell NetWare - SYNCHRONIZATION SERVICES - SIGNAL SEMAPHORE
        AX = C503h
        CX:DX = semaphore handle
Return: AL = status
            00h successful
            01h semaphore value overflowed
            FFh invalid handle
Desc:   increment the semaphore's value and signal the first process (if any)
          in the queue waiting on the semaphore
Note:   this function is supported by NetWare 4.6+, Advanced NetWare 1.0+, and
          Alloy NTNX
SeeAlso: AX=C502h