[clang][deps] Remove dependency on `tooling::ToolAction` (#149904)

The dependency scanner was initially using a fair amount of
infrastructure provided by the `clangTooling` library. Over time, the
needs for bespoke handling of command lines grew and the overlap with
the tooling library kept shrinking. I don't think the library provides
any value anymore.

I decided to remove the dependency and only reimplement the small bits
required by the scanner.

This allowed for a nice simplification, where we no longer need to
create temporary dummy `FileManager` instances (mis-named as
`DriverFileMgr` in some parts) and `SourceManager` instances to attach
to the `DiagnosticsEngine`. That code was copied from the tooling
library to support `DiagnosticConsumers` that expect these to exist. The
scanner uses a closed set of consumers and none need these objects to
exist.

The motivation for this (hopefully NFC) patch are some new restrictions
to how VFS's can be propagated in Clang that I'm working on.

0 files changed, 0 insertions, 0 deletions