egcs, fold-const.c warning fixes

[Jeffrey A Law]

  In message < 199802171746.MAA28296@caip.rutgers.edu >you write:
  > Mon Feb 16 16:04:53 1998  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
  > 
  >         * fold-const.c: Include "system.h" to get stdlib.h and stdio.h.
  >         (lshift_double): Add parentheses around + or - inside shift.
  >         (rshift_double): Likewise.
  >         (size_int_wide): Explicitly set type of `bit_p' to `int'.
  >         (optimize_bit_field_compare): Initialize variables `rnbitpos' and
  >         `rnbitsize' to 0, and `rinner' to NULL_TREE.
  >         (make_range): Initialize variable `type' to NULL_TREE.
  >         (fold): Initialize variables `arg0', `arg1' and `varop' to NULL_TREE.
  > 
  >         * Makefile.in (fold-const.o): Depend on system.h.
I installed most of this -- except for the "Initialize variables ...";
I'm going to try and test the new scheme for detecting this situation
in the next day or two.  Hopefully it'll work better and we can avoid
hacking up the sources to work around bugs in the compiler's life
analysis code :-)

jeff