compiler: Add rustc_abi dependence to the compiler

Depend on rustc_abi in compiler crates that use it indirectly but have
not yet taken on that dependency, and are not entangled in my other PRs.
This leaves an "excise rustc_target" step after the dust settles.

compiler/rustc_pattern_analysis/src/rustc.rs

@@ -1,6 +1,7 @@
 use std::fmt;
 use std::iter::once;
 
+use rustc_abi::{FIRST_VARIANT, FieldIdx, Integer, VariantIdx};
 use rustc_arena::DroplessArena;
 use rustc_hir::HirId;
 use rustc_hir::def_id::DefId;
@@ -15,7 +16,6 @@ use rustc_middle::ty::{
 use rustc_middle::{bug, span_bug};
 use rustc_session::lint;
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span};
-use rustc_target::abi::{FIRST_VARIANT, FieldIdx, Integer, VariantIdx};
 
 use crate::constructor::Constructor::*;
 use crate::constructor::{

compiler/rustc_pattern_analysis/src/rustc/print.rs

@@ -11,10 +11,10 @@
 
 use std::fmt;
 
+use rustc_abi::{FieldIdx, VariantIdx};
 use rustc_middle::bug;
 use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
 use rustc_span::sym;
-use rustc_target::abi::{FieldIdx, VariantIdx};
 
 #[derive(Clone, Debug)]
 pub(crate) struct FieldPat {