9.1.x: Fix a couple compiler warnings

[bneradt]

This pulls in a couple compiler warning fixes from later 9.x branches.

Type error:

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') {
      |           ~~~~~~~^~~~


```Maybe uninitialized error:

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; | ^~~~