improve error message when `global_asm!` uses `asm!` options
specifically, what was
error: expected one of `)`, `att_syntax`, or `raw`, found `preserves_flags`
--> $DIR/bad-options.rs:45:25
|
LL | global_asm!("", options(preserves_flags));
| ^^^^^^^^^^^^^^^ expected one of `)`, `att_syntax`, or `raw`
is now
error: the `preserves_flags` option cannot be used with `global_asm!`
--> $DIR/bad-options.rs:45:25
|
LL | global_asm!("", options(preserves_flags));
| ^^^^^^^^^^^^^^^ the `preserves_flags` option is not meaningful for global-scoped inline assembly
mirroring the phrasing of the [reference](https://doc.rust-lang.org/reference/inline-assembly.html#options).
This is also a bit of a refactor for a future `naked_asm!` macro (for use in `#[naked]` functions). Currently this sort of error can come up when switching from inline to global asm, or when a user just isn't that experienced with assembly. With `naked_asm!` added to the mix hitting this error is more likely.
9164dbd48c