- cmake: Before this patch a missing perl disabled the curl manual.
After this patch, it automatically picks up a pre-built hugehelp,
if present (= when building from a release tarball).
Follow-up to 0035ff45c5#16081
- autotools: Rework behavior when perl is missing. Before this patch
it caused a hard error when docs/manual/ca-embed were enabled.
Of these, docs were enabled by default. After this patch, doc
generation is automatically skipped, with a warning. Manual generation
falls back to using a pre-built hugehelp, or a stub if that's missing.
CA-embed is automatically skipped, with a warning.
Slight difference from cmake: When built with no perl and no pre-built
hugehelp, the manual is enabled, but the content is empty; with cmake
it's disabled proper.
Follow-up to 137aecfbf1#13514
Follow-up to 541321507e#12857
Also:
- GHA/distcheck: verify if the pre-built hugehelp makes it into curl.
- GHA/distcheck: streamline disabling perl with autotools.
- GHA/distcheck: `--disable-docs` no longer required to build without perl.
Passing it also implicitly disables the curl manual, which is
undesired in these tests.
- cmake: drop redundant `HAVE_MANUAL_TOOLS` interim variable.
- cmake: move two `set()` lines close to their counterparts.
Follow-up to 25119fbaaa#18104Closes#18118
54da6f5a32