ftp: add tracing support

- add `Curl_trc_feat_ftp` for tracing via trace config
- add macro CURL_TRC_FTP(data, fmt, ...)
- replace DEBUGF(infof()) statements in ftp.c by CURL_TRC_FTP

ftp: add tracing support

- add `Curl_trc_feat_ftp` for tracing via trace config
- add macro CURL_TRC_FTP(data, fmt, ...)
- replace DEBUGF(infof()) statements in ftp.c by CURL_TRC_FTP()
- always trace FTP connection state

Closes #13580

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curl_trc: fix build error when lacking verbose messages

Follow-up from 0b28ece657b2273
Closes #13312

lib: add trace support for client reads and writes

- add `CURL_TRC_READ()` and `CURL_TRC_WRITE()`
- use in generic client writers and readers, as well
as http headers, chunking and

lib: add trace support for client reads and writes

- add `CURL_TRC_READ()` and `CURL_TRC_WRITE()`
- use in generic client writers and readers, as well
as http headers, chunking and websockets

Closes #13223

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DoH: add trace configuration

- refs #12397 where it is dicussed how to en-/disable verbose output
of DoH operations
- introducing `struct curl_trc_feat` to track a curl feature for

DoH: add trace configuration

- refs #12397 where it is dicussed how to en-/disable verbose output
of DoH operations
- introducing `struct curl_trc_feat` to track a curl feature for
tracing
- adding `data->state.feat` optionally pointing to the feature a
transfer belongs to
- adding trace functions and verbosity checks on features
- using trace feature in DoH code
- documenting `doh` as feature for `--trace-config`

Closes #12411

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build: enable missing OpenSSF-recommended warnings, with fixes

https://best.openssf.org/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++.html
as of 2023-11-29 [1]

build: enable missing OpenSSF-recommended warnings, with fixes

https://best.openssf.org/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++.html
as of 2023-11-29 [1].

Enable new recommended warnings (except `-Wsign-conversion`):

- enable `-Wformat=2` for clang (in both cmake and autotools).
- add `CURL_PRINTF()` internal attribute and mark functions accepting
printf arguments with it. This is a copy of existing
`CURL_TEMP_PRINTF()` but using `__printf__` to make it compatible
with redefinting the `printf` symbol:
https://gcc.gnu.org/onlinedocs/gcc-3.0.4/gcc_5.html#SEC94
- fix `CURL_PRINTF()` and existing `CURL_TEMP_PRINTF()` for
mingw-w64 and enable it on this platform.
- enable `-Wimplicit-fallthrough`.
- enable `-Wtrampolines`.
- add `-Wsign-conversion` commented with a FIXME.
- cmake: enable `-pedantic-errors` the way we do it with autotools.
Follow-up to d5c0351055d5709da8f3e16c91348092fdb481aa #2747
- lib/curl_trc.h: use `CURL_FORMAT()`, this also fixes it to enable format
checks. Previously it was always disabled due to the internal `printf`
macro.

Fix them:

- fix bug where an `set_ipv6_v6only()` call was missed in builds with
`--disable-verbose` / `CURL_DISABLE_VERBOSE_STRINGS=ON`.
- add internal `FALLTHROUGH()` macro.
- replace obsolete fall-through comments with `FALLTHROUGH()`.
- fix fallthrough markups: Delete redundant ones (showing up as
warnings in most cases). Add missing ones. Fix indentation.
- silence `-Wformat-nonliteral` warnings with llvm/clang.
- fix one `-Wformat-nonliteral` warning.
- fix new `-Wformat` and `-Wformat-security` warnings.
- fix `CURL_FORMAT_SOCKET_T` value for mingw-w64. Also move its
definition to `lib/curl_setup.h` allowing use in `tests/server`.
- lib: fix two wrongly passed string arguments in log outputs.
Co-authored-by: Jay Satiro
- fix new `-Wformat` warnings on mingw-w64.

[1] https://github.com/ossf/wg-best-practices-os-developers/blob/56c0fde3895bfc55c8a973ef49a2572c507b2ae1/docs/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C%2B%2B.md

Closes #12489

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build: variadic macro tidy-ups

- delete unused `HAVE_VARIADIC_MACROS_C99/GCC` feature checks.
(both autotools and CMake.)
- delete duplicate `NULL` check in `Curl_trc_cf_infof()`.

build: variadic macro tidy-ups

- delete unused `HAVE_VARIADIC_MACROS_C99/GCC` feature checks.
(both autotools and CMake.)
- delete duplicate `NULL` check in `Curl_trc_cf_infof()`.
- fix compiler warning in `CURL_DISABLE_VERBOSE_STRINGS` builds.
```
./lib/cf-socket.c:122:41: warning: unused parameter 'data' [-Wunused-parameter]
static void nosigpipe(struct Curl_easy *data,
^
```
- fix `#ifdef` comments in `lib/curl_trc.{c,h}`.
- fix indentation in some `infof()` calls.

Follow-up to dac293cfb7026b1ca4175d88b80f1432d3d3c684 #12167

Cherry-picked from #12105
Closes #12210

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lib: apache style infof and trace macros/functions

- test for a simplified C99 variadic check
- args to infof() in --disable-verbose are no longer disregarded but
must compile.

lib: apache style infof and trace macros/functions

- test for a simplified C99 variadic check
- args to infof() in --disable-verbose are no longer disregarded but
must compile.

Closes #12167
Fixes #12083
Fixes #11880
Fixes #11891

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misc: spellfixes

Closes #11730

trace: make tracing available in non-debug builds

Add --trace-config to curl

Add curl_global_trace() to libcurl

Closes #11421