Avoid signed/unsigned warnigs

[John David Anglin]

> My gut feeling says all this is excessive but I could be wrong.

On further thought, it seems silly to cast mode_size's to signed int's
everywhere.  The proper fix is to change to unsigned all the mode_size
variables.  This requires adding some infrastructure to rtl.h to handle
`unsigned HOST_WIDE_INT' (eg., UINTVAL).  If you are willing to make
and test all the necessary changes, that would be great.  If not, then
we can either live with the warnings, or revert the declaration for
mode_size in machmode.h back to `const int' with a FIXME comment.

I got interested in your patch when I noted some of the warnings compiling
pa.c were caused by this problem.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)