Extend list of compilation options for source builds

[eschabell]

The list of compilation options is not up to date in the DOC. I'm in the process of making a PR for an update, but I have the impression that certain variables are no longer useful. Here is a list:
FLB_FILTER_ALTER_SIZE
FLB_FILTER_THROTTLE_SIZE
FLB_FILTER_LUA_USE_MPACK

It would be good to add in the pipelines a consistency check between the variables here:

• https://github.com/fluent/fluent-bit/blob/master/CMakeLists.txt
• https://github.com/fluent/fluent-bit/blob/master/cmake/plugins_options.cmake
• https://github.com/fluent/fluent-bit-docs/blob/master/installation/sources/build-and-install.md

Note that this was originally raised by @tguenneguez and addressed with doc PR #1386, but aged out of making sense to fix all the conflicts, so starting fresh here.

[eschabell]

@patrick-stephens this is a big swing at this list, long overdue updates, so I'm really interested in a review by @cosmo0920 at the very least. If we close it out, then it's never reviewed.

[eschabell]

@cosmo0920 would you mind taking a look at this: #2145

if you prefer as it's been merged: https://docs.fluentbit.io/manual/installation/downloads/source/build-and-install

[patrick-stephens]

Yeah I merged as I think easier to fix anything outstanding but get all the updates in for folks to see now.

[eschabell]

Moving on then...