[clangd] Introduce PostingList interface
This patch abstracts `PostingList` interface and reuses existing
implementation. It will be used later to test different `PostingList`
representations.
No functionality change is introduced, this patch is mostly refactoring
so that the following patches could focus on functionality while not
being too hard to review.
Reviewed By: sammccall, ioeric
Differential Revision: https://reviews.llvm.org/D51982
llvm-svn: 342155
GitOrigin-RevId: 249c5864cf9657a320e427318a879ba809e84b1a
8 files changed