packages: Fix build with libucl 0.9.3

[ivy]

Summary

In libucl 0.9.3, macros and includes are disabled by default when
creating a new UCL parser. This breaks the package build, which
relies on includes. Fix this by explicitly passing zero flags
to ucl.parser().

Fixes: abda442d92fd ("contrib/libucl: Import libucl 0.9.3")
Reported by: [e-mail]
Sponsored by: https://www.patreon.com/bsdivy

[ivy]

unfortunately, even if we land this fix, it will be impossible to build any version without the fix (e.g., 15.0 or 14.4) on a version post libucl 0.9.3. this is a rather less than ideal situation, so perhaps someone has a better suggestion.

(we should fix this for the future by using bootstrap flua for pkgbase, but that doesn't fix existing releases.)

[bofh]

I have added @des and @kevans who were mentioning something about this somewhere.

[ivy]

i briefly discussed this with kevans and he suggested we could revert the specific libucl commit which broke this[0] which i would be inclined to support.

[0] https://github.com/vstakhov/libucl/commit/8a0294f9eaa4e70342e562cb92792bbe3df90e70

[kevans]

In D56266#1287504, @ivy wrote:

i briefly discussed this with kevans and he suggested we could revert the specific libucl commit which broke this[0] which i would be inclined to support.

[0] https://github.com/vstakhov/libucl/commit/8a0294f9eaa4e70342e562cb92792bbe3df90e70

CC @bapt -- this is specific to the lua bindings, and I think nuageinit is the only other consumer.

[ivy]

btw, even if we revert that change, i think we should still land this commit: it's backward-compatible with the previous libucl (where flags just defaulted to zero) and it will be useful if we want to un-revert the libucl change later.

[bapt]

nuageinit is not impacted as it only parses json with libucl
I agree we should anyway land this

[kevans]

In D56266#1287587, @bapt wrote:

nuageinit is not impacted as it only parses json with libucl
I agree we should anyway land this

My concern with nuageinit is specifically if we revert the libucl change that disables macros in the parser- presumably up until that change one could still inject variables and macros into cloud-init config and do potentially bad things (which we would reintroduce by reverting temporarily), but given that we're using the cloud-init config to drive configuration of the system that's probably not really a concern?