ccl: add integer overflow checks

ccl: add integer overflow checks

* ccl.c (CCL_CODE_MAX, GET_CCL_RANGE, GET_CCL_CODE, GET_CCL_INT):
(IN_INT_RANGE): New macros.
(ccl_driver): Use them to check for integer overflow when
decoding a CCL program.  Many of the new checks are whether XINT (x)
fits in int; it doesn't always, on 64-bit hosts.  The new version
doesn't catch all possible integer overflows, but it's an
improvement.