Before this patch `pkg-config`-based detection was ignored, and used
solely as a path hint for native detection.
- fix `pkg_search_module()` result prefix to match what code expects:
`_GSS` (was: `_GSS_PKG`). Update variable that were in sync with old
prefix.
- update the pkg-config codepath to use `_GSS_MODULE_NAME` to detect
GSS flavour. This requires CMake 3.16.
Otherwise fall back to the old method. (The old method doesn't seem to
work anymore (?) as of CMake 3.30.1. Documented
`<prefix>_<modulename>_VERSION` variable is defined, but empty.)
- update the pkg-config codepath to use `_GSS_VERSION` set by CMake.
Resort to the old code when this variable is empty. (The old code
doesn't seem to work anymore (?) as of CMake 3.30.1)
- fix pkg-config codepath to set the documented result variables.
- align native detection variable names with those generated by
`pkg_search_module()` in the pkg-config codepath.
- GHA/macos: enable GSS Heimdal in a cmake job.
Uses the native detection.
- GHA/linux: enable GSS Heimdal in cmake and autotools jobs.
CMake uses `pkg-config`-based detection.
- suppress test 2077 and 2078 results on Linux + Heimdal.
```
FAIL-IGNORED 2077: 'curl --fail --negotiate to unauthenticated service fails' HTTP, HTTP GET, GSS-API
FAIL-IGNORED 2078: 'curl --negotiate should not send empty POST request only' HTTP, HTTP GET, GSS-API
```
Failing with valgrind errors in both autotools and cmake builds:
https://github.com/curl/curl/actions/runs/10282222581/job/28453472068?pr=14430#step:38:3638https://github.com/curl/curl/actions/runs/10282222581/job/28453473398?pr=14430#step:38:7831Closes#14430
146759716c