Auto merge of #47087 - Zoxc:incr_no_in_ignore, r=michaelwoerister

Replace uses of DepGraph.in_ignore with DepGraph.with_ignore

I currently plan to track tasks in thread local storage. Ignoring things in a closure ensures that the ignore tasks do not overlap the beginning or end of any other task. The TLS API will also use a closure to change a TLS value, so having the ignore task be a closure also helps there.

It also adds `assert_ignored` which is used before a `TyCtxt` is created. Instead of adding a new ignore task this simply ensures that we are in a context where reads are ignored.

r? @michaelwoerister

diff --cc src/librustc/ty/maps/on_disk_cache.rs
Simple merge

diff --cc src/librustc_metadata/encoder.rs
Simple merge

diff --cc src/librustc_trans/assert_module_sources.rs
Simple merge