Relicense shootout-spectralnorm.rs to the shootout license

Everyone agreed.

Fix #17064
Relicense shootout-fasta.rs ti the shootout license.

Everyone agreed.

Fix #17072
test: Un-ignore some GDB pretty printing tests

I've confirmed that these are working on the snapshot builders

Closes #16919
auto merge of #17335 : TeXitoi/rust/relicense-shootout, r=brson

Everyone agreed.  Fix #17064, fix #17072 

@brson OK?
auto merge of #17341 : alexcrichton/rust/unignore, r=brson

I've confirmed that these are working on the snapshot builders

Closes #16919
syntax: use an index in CodeMap instead of Gc for ExpnInfo.
rustc: fix fallout from removing the use of Gc for ExpnInfo.
Fix fallout in tests from removing the use of Gc in ExpnInfo.