Update dev-libs/boost

Update boost to support new perl.
Move back to EAPI 7
Replace usev with usex since we are still at EAPI 7

Allow current python to work (Keep supported python to python3_{6..9})

Add LFS (Large File Support) C and C++ options.

BUG=b:268190737
TEST=Build herobrine image.

Change-Id: Ied3197d3bc750974d2775bb21fabf6511ee12548
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/4235874
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
16 files changed