Change svr4 references to sysv4.
* source.c: Move declaration of external function index to
front of file so it is in scope for all references.
* utils.c (error, fatal): Make definitions consistent with
defs.h declarations (declared as "volatile void").
only differences were in the specific trap vectors used and whether or not
an fpu was present. These are now handled by appropriate definitions of
BPT_VECTOR and HAVE_68881 respectively. Other minor obvious cleanups.
Minor spelling correction in valops.c.