Use <stddef.h> as a source for size_t as suggested by ANSI in preference
to <sys/types.h> (as suggested by POSIX), and make sure that the check
includes linkin so it won't result in a false positive in platforms that
allow link time resolution of unknown objects (ex: AIX with lxc)

Made PCRE2_UCP the default in UTF mode in pcre2grep, and added new options --case-restrict and --no-ucp.

`ucptest` was misbehaving and showing the wrong properties and
finding the wrong characters.

Compilers had become far more creative about optimizing code that
might be considered undefined behaviour, so improve our integer
overflow checking to prevent any possible miscompilations.

While at it, expand the use of the checks to pcre2test to fix a
similar problem to the one that was tackled in pcre2_compile.

Prefer (if available) a builtin provided by the compiler.

Starting with Unicode 15, the provided DerivedBidiClass data file
reports different default values to use for unassigned characters
in different groups.

Process the additional hints for that specific file, and allow
overriding the values later if more specific.

Since that was previously forbidden, change get_other_case() to
report when no valid value could be provided and allow skipping
conflicting rule lines that required that restriction.

While at it, Allow using the long identifiers in `ucptest` with
the `find bidi` command (underscores also allowed).

* ucptest: regenerate testoutput

Last sync with 1a5fcd (Remove unused variables in ucptest.c and update test data
for added properties, 2022-04-25), and showing significant differences.

* fix `findprop +` with UTF-8 characters and duplicated other case

Reverting several reserved characters that were removed from the
previous release, and that are only referencing as "@missing@ in
DerivedBidiClass.txt

It doesn't change much in practice, but helps clarify the interfaces
of some functions that were either documented with the wrong type or
had mismatching types between declaration and implementation.

Recent code uses C99 syntax (as reported in #163, and therefore it
will fail to build unless C99 (or higher) support is required by the
compiler (gcc >= 5 does it by default).

For those unfortunate to need an older compiler that does require a
flag to enable that, make sure that both autoconf and cmake make it
explicit.

While testing the change with the ancient autoconf version listed as
a prerequisite, noticed that the LT_INIT syntax introduced with 91485e5d
(Update configure.ac for latest version of autoconf., 2021-02-02), was
not supported, so update the autoconf minimum as well.

When using -t or its variants the timing results with a modern CPU
where not very significant even with 4 decimal digits.

While at it, move the factor calculation that can be done with
integer arithmetic and even optimized out for the more common case
when CLOCKS_PER_SEC == 1000000 out of the denominator.

Since PCRE2 10.41, the match data contains a pointer to a vector of
frames allocated in the heap and that are used by pcre2_match()
when doing non JIT matches.

There is though, no outside visibility on the size of it, and therefore
the memory it uses is locked away until match_data itself is freed.

Add an API that allows getting that value, so an application could
decide based on its own experienced memory pressure to keep reusing
that match_data or not.

While at it, update the documentation of other related functions for
clarity.

If a LIMIT_HEAP value once converted to bytes is larger than UINT_MAX
would result in a bogus setting that could trigger a matching failure
as shown by the following:

  PCRE2 version 10.42 2022-12-11
    re> /(*LIMIT_HEAP=4194304)a/
  data> a
  Failed: error -63: heap limit exceeded

Remove the multiplication and instead keep track of the maximum heap
allowed in KB as was done originally.

Aditionally, add a check to avoid overflowing a PCRE2_SIZE while
doubling the heap used and that could result in a crash (only on
systems with a 32-bit PCRE2_SIZE and using non standard settings).

Unlike the original, this code avoids rounding the heapframes_size
to the frame_size at the allocation time, which simplifies the logic
and wasn't really needed.

Fixes: d90fb238 (Refactor match_data() to always use the heap instead
       of having an initial frames vector on the stack..., 2022-07-27)
Closes: #183

e8cdae3c (Correct an incorrect cast., 2017-04-14) started changing
some of the casts to fit the type of the error offset variable, so
complete that, and for consistency, add the same type of casts to
the non UTF-8 code.

Update the ManyConfigTests to include new POSIX freestanding test, add a JIT test in a non-source directory, and update selectors