* libc/sys/rtems/include/limits.h, libc/sys/rtems/sys/param.h,
libc/sys/rtems/sys/syslimits.h: Update to be in sync with what
constants are defined in each file in the shared versions in
libc/include.
* libc/sys/rtems/crt0.c: Define extra symbols on SH and HP-PA to
autoconf can link programs.
* libc/include/machine/types.h: Explicitly specify signed on
intXX_t types to ensure they are signed.