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Avoid negation of signed integers in C that may hold INT*_MIN.

Reported by minoki.
Recent C compilers 'take advantage' of the undefined behavior.
This completely changes the meaning of expressions like (k == -k).

(cherry picked from commit 8a5e398c5)

This patch changes all possibly dangerous -x operations on integers to
the corresponding two's complement. Also, it removes all related UBSAN
suppressions, since they are fixed.

Also, this patch limits the `bit.tohex()` result by 254 characters.

There is no testcase for `strscan_oct()`, `strscan_dec()` or/and
`STRSCAN_U32` format since first the unary minus is parsed first and
only after the number itself is parsed during parsing C syntax. So the
error is raised in `cp_expr_prefix()` instead. For parsing the exponent
header, there is no testcase, since the power is limited by
`STRSCAN_MAXEXP`.

Sergey Kaplun:
* added the description and the test for the problem

Part of tarantool/tarantool#9924
Relates to tarantool/tarantool#8473

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