Closes GH-4394

These are already defined in zend_portability.h.

The APACHE symbol was used in very early PHP versions to indicate the
Apache module usage. Since PHP 4 this is no longer used in the code.

By introducing a hook that is called whenever one of
internal_encoding / input_encoding / output_encoding changes, so
that mbstring can adjust it's internal state.

This also makes internal_encoding work with zend multibyte.

Checking for the strerror function presence is no longer needed since it
is part of the C89 standard [1] and can be safely assumed that all
current systems have it.

Check in the configure.ac and Windows defined symbol are still left
until the file library (libmagic) will be updated.

[1]: https://port70.net/~nsz/c/c89/c89-draft.html

The `<limits.h>` header file is part of the standard C89 headers [1]
and on current systems can be included unconditionally.

Since PHP requires at least C89 or greater, the `HAVE_LIMITS_H` symbol
defined by Autoconf in configure.ac [2] can be ommitted and simplifed
however due to bundled file library (libmagic) and timelib still using
it, the removal there was omitted and done only in Zend.m4 file.

Current bundled libraries libtime, oniguruma, and libmagic still include
partial `HAVE_LIMITS_H` usage and will be more refactored when this is
possible.

Refs:
[1] https://port70.net/~nsz/c/c89/c89-draft.html#4.1.2
[2] https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/headers.m4

The AC_CHECK_TYPE was refactored in more recent versions of Autoconf
and the call with two arguments is obsolete and not recommended anymore.

This patch also refactors some leftovers of using ulong and uint which
are not standard nor common usages of types in C.

The ulong can be used as zend_ulong and uint usage is actually
`unsigned int`.

The usage of HAVE_ULONG removed since it is not used in current code
base.

Legacy edgecase for some legacy HPUX systems removed:
- sys/stream.h header is not checked and the HAVE_SYS_STREAM_H is
  not defined with current build system.

- flags are unsigned int
- max_allowed_packet changed to unsigned int

Autoconf 2.59d (released in 2006) [1] started promoting several macros
as not relevant for newer systems anymore, including the `AC_HEADER_STDC`.

This macro checks if given system has C89 compliant header files such
as `<string.h>`, `<stdlib.h>`, `<stdarg.h>`, `<float.h>`,... and defines
the `STDC_HEADERS` symbol [2]. Case is that current systems should be
well supported with at least C89 standard headers [3].

Given headers are still additionally checked with the `AC_PROG_CC`
macro, yet not needed anyway.

Additionally, the HAVE_MEMCPY check has been removed. The memcpy
function is standardized by C89 and later.

Refs:
[1] http://git.savannah.gnu.org/cgit/autoconf.git/tree/NEWS
[2] https://www.gnu.org/software/autoconf/manual/autoconf-2.69/autoconf.html
[3] https://port70.net/~nsz/c/c89/c89-draft.html#4.1.2