xgcc failure, 970929 on i586-linux, target mips64-elf

[Jim Wilson]

	/usr/src/egcs-970929/gcc/dwarf2out.c:540: failed assertion `n_ranges < 5'

This is a bug in Jason's dwarf2 exception handling support.
I have been waiting to see if he had any suggestions on how to solve it,
but haven't heard back from him yet.  We will need to do something about it
soon.

Perhaps we should fix init_reg_modes in regclass.c to use reg_raw_mode[i-1]
instead of word_mode.  The choice of word_mode is somewhat arbitrary, so
using something else equally arbitrary shouldn't make any real difference
to the rest of the compiler, and this change would allow the dwarf2 EH
support to work.

Jim