Auto merge of #32806 - brson:fix-features, r=alexcrichton

Set the version number for stabilization of braced_empty_structs

and augmented_assignment to 1.8.0.

Per the comments, the numbers in this table reflect the "current
status".

cc @rust-lang/libs @rust-lang/lang

Discovered this while hunting for 1.8 features. I'm afraid there may be more of these that are incorrect and we may have created a mess.

diff --cc src/libsyntax/feature_gate.rs
Simple merge