(by rrh) Added three extra data types: GFLOAT, HFLOAT and OCTA

(by rrh) Added three extra data types: GFLOAT, HFLOAT and OCTA
Allowed c2 to optimize instructions manipulating G and H format instructions
just as it can now optimize F and D format instructions.
c22.c now is mostly empty; data for c2 is now stored in as/instrs, to
minimize the duplication that existed formerly.
New data types have ordinal assignments after existing ones;
because of the flakiness of c2, it is not clear what this may break.

SCCS-vsn: old/pcc/c2.vax/c2.h 4.5
SCCS-vsn: old/pcc/c2.vax/c21.c 4.8
SCCS-vsn: old/pcc/c2.vax/c22.c 4.2