Implenent missing flags

[uvlad7]

Implemented IN_EXCL_UNLINK and IN_MASK_CREATE
guarded IN_ONLYDIR and IN_DONT_FOLLOW, affects really old kernels only

[uvlad7]

The fail is so strange, it works on my machine with ruby 3.0.6 and 3.4.2

'already initialized constant' alerts are also strange

[uvlad7]

The version is "6.11.0.pre.1015.pre.azure" and it still works fine locally, but I noticed it isn't parsed properly (UPD: it is, just drops trailing 0 as intended)

[uvlad7]

So it works fine on all MRI rubies after 3.0.7, so it seems to be due to older rubygems ver
And 'etc' is a problem on JRuby so it needs to be optional, but it'd require a separate 'java' gem version or to remove 'etc' from dependencies. I think the latter is easier, because 'etc' is a default gem as of Ruby '3.4.2', and while it's still recommended to add these as dependencies, as they might become bundled/regular gems in the future, rn it'll work

[uvlad7]

Draft because not all unames are handled ok - "6.6.72+" for example

[uvlad7]

So I decided not to check kernel version

• not reliable anyway
• linux 4.18 is pretty old
• it won't silently ignore unrecognized flags, EINVAL is raised