[boost-gil] remove dependency boost-filesystem

[Osyotr]

This dependency is optional and only used to build and run tests and examples.
See https://github.com/boostorg/gil#requirements
However, there is also BOOST_GIL_IO_ADD_FS_PATH_SUPPORT which enables
boost::filesystem::path support for IO functions, but since users have to define
it manually, they must install the dependency manually, too.

A little benefit is that there is no need to build anything anymore: GIL itself and all its dependencies are header-only.

[strega-nil-ms]

I don't like doing this without making sure that this doesn't change over time when people run generate-boost.ps1; @ras0219 what do you think?

[Osyotr]

@strega-nil-ms is vcpkg.json for autogenerated? I can't find anything related.
git grep gil over entire vcpkg directory prints only this port and mapnik, which already explicitly declares boost-filesystem dependency.

[autoantwort]

is vcpkg.json for autogenerated?

Yes the boost vcpkg.json files are autogenerated by scripts/boost/generate-ports.ps1

[Osyotr]

@autoantwort I see. So dependencies of boost libraries are determined by their includes and even though boost-filesystem includes are guarded by #ifdef ..., dependency is added nevertheless. The only solution I see now is to forcefully remove it from dependency list here

[PhoebeHui]

cc @yurybura

[strega-nil-ms]

I've made the required changes to generate-ports.ps1

[yurybura]

After re-run generation script the dependency will be added again. Script's logic must be modified too. I can do this in #20432.

[yurybura]

Done by @strega-nil-ms )

[BillyONeal]

#20432 restores compat between generate-ports.ps1 and all boost ports and should land first.

[BillyONeal]

I pushed a merge with master to get #20432 and ensured that generate-ports.ps1 results in no edits

[Osyotr]

I pushed a merge with master to get #20432 and ensured that generate-ports.ps1 results in no edits

Thanks!