Auto merge of #46895 - ricochet1k:macro-lifetimes, r=jseyfried

Allow lifetimes in macros

This is a resurrection of PR #41927 which was a resurrection of #33135, which is intended to fix #34303.

In short, this allows macros_rules! to use :lifetime as a matcher to match 'lifetimes.

Still to do:
- [x]  Feature gate

diff --cc src/libsyntax/parse/parser.rs
Simple merge