SCO vs. the monster macro

> But we don't want that if they use a good compiler under SCO.  I have
> asked them to run src/tools/ccsym and send the output.  Should be
> something unique in there.

On SCO, ccsym becomes /bin/cc -b elf -ii -E foo.c, which after filtering
gives the symbols below. If I omit "-b elf", the last line is replaced
by the two lines
'-D_M_COFF'
'-D_SCO_COFF'

How about _SCO_DS as the define when testing for SCO's native
compiler? (I confess ignorance as to SCO's intended use of this symbol.)

'-D__i386'
'-D_SCO_DS=1'
'-D__unix'
'-D_M_I386'
'-D_M_XENIX'
'-D_M_UNIX'
'-D_SCO_C_DIALECT=1'
'-D_STRICT_NAMES'
'-D_M_I86'
'-D_M_I86SM'
'-D_M_SDATA'
'-D_M_STEXT'
'-D_M_BITFIELDS'
'-D_M_INTERNAT'
'-D_M_SYS5'
'-D_M_SYSV'
'-D_M_SYSIII'
'-D_M_WORDSWAP'
'-Di386'
'-Dunix'
'-DM_I386'
'-DM_UNIX'
'-DM_XENIX'
'-D_SCO_XPG_VERS=4'
'-D_SCO_ELF'