Merge #443 #444 #447

443: Fix raw identifier parsing. r=dkm a=dkm

Lexer::parse_raw_identifier added the first character twice.

Adds tests for a simple raw identifier, a keyword as raw identifier and
xfail tests for a single underscore and forbidden keyword (crate) as raw
identifier.

To help error diagnostics continue after parse_raw_identifier failed in
Lexer::build_token.

Fixes: https://github.com/Rust-GCC/gccrs/issues/426

444: Initialize crateNumItr in rust-hir-map to zero. r=dkm a=dkm

valgrind complains whenever a crate number is used because they are all
derived from the initial crateNumItr in the rust-hir-map Mapping which
is never initialized. This isn't technically a bug because all that is
required is for crate numbers to be unique. But it could cause
non-deterministic behaviour when crate numbers are used for sorting.
And it makes the valgrind output really noisy.

With this patch and configure --enable-valgrind-annotations running
rust1 should not give any valgrind errors.

447: Mention the identifier that was unused in ScanUnused. r=dkm a=dkm

The ScanUnused class would only mention some name was unused.
Add the actual identifier name that is unused to help the user.

Note that this warning might produce a similar warning as the
ScanDeadcode class produces if the indentifier is a function.


Co-authored-by: Mark Wielaard <mark@klomp.org>