gccrs: Add all rust keywords (except priv) to the follow-set of `:vis` when parsing macro rules

Previously, the following macro rules were rejected by gccrs:
```Rust
macro_rules! {
    ($v:vis <KEY_WORD>) => { ... };
}
```

This PR fixes so the above code is accepted by the compiler for all key words like `async` or `unsafe`.
The only exception is the keyword `priv` which is not allowed.
See [this page](https://doc.rust-lang.org/reference/macro-ambiguity.html) for reference. Especially the following excerpt:
> FOLLOW(vis) = {,l any keyword or identifier except a non-raw priv; any token that can begin a type; ident, ty, and path nonterminals}.

Fixes #1060

gcc/rust/ChangeLog:

	* parse/rust-parse.cc: fix follow-sets

gcc/testsuite/ChangeLog:

	* rust/compile/macro47.rs: Test that :vis can be followed by some keywords
	* rust/compile/macro48.rs: Test that :vis cannot be followed by the keyword priv

Signed-off-by: Tage Johansson <frans.tage@gmail.com>

0 files changed, 0 insertions, 0 deletions