- bearssl, c-ares, gss, libpsl, libssh2, mbedtls:
Before this patch these Find modules returned results via
`<NAME>_INCLUDE_DIR` and `<NAME>_LIBRARY`.
This patch makes them return `<NAME>_INCLUDE_DIRS` (note the `S`)
and `<NAME>_LIBRARIES` like other modules already did.
- bearssl, mbedtls:
Before this patch these Find modules allowed custom configuration
via `<NAME>_INCLUDE_DIRS` (note the `S`).
This patch makes them accept `<NAME>_INCLUDE_DIR`, like the rest of
the modules did.
Deprecate the old variables, but keep accepting them for
compatibility.
- bearssl: add missing `mark_as_advanced()` call.
Closes#14542
db39c668a8