lib/src: white space edits to comply better with code style

... as checksrc now finds and complains about these.

Closes #14921

build: untangle `UNITTESTS` and `DEBUGBUILD` macros

- fix `DEBUGBUILD` guards that should be `UNITTESTS`, in libcurl code
used by unit tests.
- fix guards for libcurl functions use

build: untangle `UNITTESTS` and `DEBUGBUILD` macros

- fix `DEBUGBUILD` guards that should be `UNITTESTS`, in libcurl code
used by unit tests.
- fix guards for libcurl functions used in unit tests only.
- sync `UNITTEST` attribute between declarations and definitions.
- drop `DEBUGBUILD` guard from test `unit2600`.
- fix guards for libcurl HSTS code used by both a unit test (`unit1660`)
and `test0446`.
- update an existing AppVeyor CI job to test the issues fixed.

This fixes building tests with `CURLDEBUG` enabled but `DEBUGBUILD`
disabled. This can happen when building tests with CMake with
`ENABLE_DEBUG=ON` in Release config, or with `ENABLE_CURLDEBUG=ON`
and _without_ `ENABLE_DEBUG=ON`. Possibly also with autotools
when using `--enable-curldebug` without `--enable-debug`.

Test results:
- before:
https://ci.appveyor.com/project/curlorg/curl/builds/49835609
https://ci.appveyor.com/project/curlorg/curl/builds/49898529/job/k8qpbs8idby70smw
https://github.com/curl/curl/actions/runs/9259078835/job/25470318167?pr=13798#step:13:821
- after: https://ci.appveyor.com/project/curlorg/curl/builds/49839255
(the two failures are unrelated, subject to PR #13705)

Ref: #13592 (issue discovery)
Ref: #13689 (CI testing this PR with `DEBUGBUILD`/`CURLDEBUG` combinations)
Closes #13694

show more ...

http2: header conversion tightening

- fold the code to convert dynhds to the nghttp2 structs
into a dynhds internal method
- saves code duplication
- pacifies compiler analyzer

http2: header conversion tightening

- fold the code to convert dynhds to the nghttp2 structs
into a dynhds internal method
- saves code duplication
- pacifies compiler analyzers

Closes #12097

show more ...

http: h1/h2 proxy unification

- use shared code for setting up the CONNECT request
when tunneling, used in HTTP/1.x and HTTP/2 proxying
- eliminate use of Curl_buffer_send() and ot

http: h1/h2 proxy unification

- use shared code for setting up the CONNECT request
when tunneling, used in HTTP/1.x and HTTP/2 proxying
- eliminate use of Curl_buffer_send() and other manipulations
of `data->req` or `data->state.ulbuf`

Closes #11808

show more ...

lib: remove unused functions, make single-use static

Closes #11174

http2: support HTTP/2 to forward proxies, non-tunneling

- with `--proxy-http2` allow h2 ALPN negotiation to
forward proxies
- applies to http: requests against a https: proxy only,

http2: support HTTP/2 to forward proxies, non-tunneling

- with `--proxy-http2` allow h2 ALPN negotiation to
forward proxies
- applies to http: requests against a https: proxy only,
as https: requests will auto-tunnel
- adding a HTTP/1 request parser in http1.c
- removed h2h3.c
- using new request parser in nghttp2 and all h3 backends
- adding test 2603 for request parser
- adding h2 proxy test cases to test_10_*

scorecard.py: request scoring accidentally always run curl
with '-v'. Removed that, expect double numbers.

labeller: added http1.* and h2-proxy sources to detection

Closes #10967

show more ...

lib: add `bufq` and `dynhds`

Adding `bufq`:
- at init() time configured to hold up to `n` chunks of `m` bytes each.
- various methods for reading from and writing to it.
- `peek`

lib: add `bufq` and `dynhds`

Adding `bufq`:
- at init() time configured to hold up to `n` chunks of `m` bytes each.
- various methods for reading from and writing to it.
- `peek` support to get access to buffered data without copy
- `pass` support to allow buffer flushing on write if it becomes full
- use case: IO buffers for dynamic reads and writes that do not blow up
- distinct from `dynbuf` in that:
- it maintains a read position
- writes on a full bufq return CURLE_AGAIN instead of nuking itself
- Init options:
- SOFT_LIMIT: allow writes into a full bufq
- NO_SPARES: free empty chunks right away
- a `bufc_pool` that can keep a number of spare chunks to
be shared between different `bufq` instances

Adding `dynhds`:
- a straightforward list of name+value pairs as used for HTTP headers
- headers can be appended dynamically
- headers can be removed again
- headers can be replaced
- headers can be looked up
- http/1.1 formatting into a `dynbuf`
- configured at init() with limits on header counts and total string
sizes
- use case: pass a HTTP request or response around without being version
specific
- express a HTTP request without a curl easy handle (used in h2 proxy
tunnels)
- future extension possibilities:
- conversions of `dynhds` to nghttp2/nghttp3 name+value arrays

Closes #10720

show more ...