Fix Rocky Linux 8 arm64 GCC Compiler Warnings

[bneradt]

This patch addresses the compiler warnings raised by the GCC 11.2.1
compiler on Rocky Linux 8 arm64:

-Werror=shift-negative-value in I_Continuation.h:

In file included from src/ts_asf_master_test_build/iocore/eventsystem/I_Action.h:29,
                 from src/ts_asf_master_test_build/iocore/eventsystem/I_EventSystem.h:32,
                 from src/ts_asf_master_test_build/iocore/eventsystem/I_VConnection.h:29,
                 from QUICStreamVCAdapter.cc:24:
src/ts_asf_master_test_build/iocore/eventsystem/I_Continuation.h: In instantiation of _constexpr int (Continuation::* continuation_handler_void_ptr(int (C::*)(int, T*)))(int, void*) [with C = QUICStreamVCAdapter; T = void; ContinuationHandler = int (Continuation:
:*)(int, void*)]_:
QUICStreamVCAdapter.cc:29:3:   required from here
src/ts_asf_master_test_build/iocore/eventsystem/I_Continuation.h:74:10: error: left shift of negative value [-Werror=shift-negative-value]
   74 |   return static_cast<ContinuationHandler>(fp2);
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-Werror=sign-compare in fastlz.cc:

fastlz.cc: In function _void flz_copy64(uint8_t*, const uint8_t*, uint32_t)_:
fastlz.cc:209:17: error: comparison of integer expressions of different signedness: _int_ and _uint32_t_ {aka _unsigned int_} [-Werror=sign-compare]
  209 |   for (c = 0; c < count * 8; ++c) {
      |               ~~^~~~~~~~~~~

-Werror=maybe-uninitialized in header_rewrite:

header_rewrite/conditions.cc: In static member function _static void ConditionInbound::append_value(std::string&, const Resources&, NetworkSessionQualifiers)_:
header_rewrite/conditions.cc:1131:56: error: _tags_ may be used uninitialized [-Werror=maybe-uninitialized]
 1131 |     TSHttpTxnClientProtocolStackGet(res.txnp, tags.size(), tags.data(), &count);
      |                                               ~~~~~~~~~^~
In file included from header_rewrite/conditions.cc:29:
/opt/rh/gcc-toolset-11/root/usr/include/c++/11/array:176:7: note: by argument 1 of type _const std::array<const char*, 8>*_ to _constexpr std::array<_Tp, _Nm>::size_type std::array<_Tp, _Nm>::size() const [with _Tp = const char*; long unsigned int _Nm = 8]_ declared here
  176 |       size() const noexcept { return _Nm; }
      |       ^~~~
header_rewrite/conditions.cc:1128:33: note: _tags_ declared here
 1128 |     std::array<char const *, 8> tags;
      |                                 ^~~~

-Werror=type-limits in traffic_dump:

experimental/traffic_dump/json_utils.cc: In function _int {anonymous}::esc_json_out(const char*, int64_t, std::ostream&)_:
experimental/traffic_dump/json_utils.cc:117:18: error: comparison is always true due to limited range of data type [-Werror=type-limits]
  117 |       if ('\x00' <= c && c <= '\x1f') {
      |           ~~~~~~~^~~~

[ywkaras]

Use of reinterpret_cast may result in a wild this pointer, and it bypasses some compile-time checking.

[zwoop]

Cherry-picked to v9.2.x