Remove trait CoverageInfoMethods, since non-LLVM backends don't need it

These methods are only ever called from within `rustc_codegen_llvm`, so they
can just be declared there as well.

compiler/rustc_codegen_ssa/src/traits/coverageinfo.rs

@@ -1,25 +1,7 @@
 use super::BackendTypes;
-use rustc_hir::def_id::DefId;
 use rustc_middle::mir::Coverage;
 use rustc_middle::ty::Instance;
 
-pub trait CoverageInfoMethods<'tcx>: BackendTypes {
-    fn coverageinfo_finalize(&self);
-
-    /// Codegen a small function that will never be called, with one counter
-    /// that will never be incremented, that gives LLVM coverage tools a
-    /// function definition it needs in order to resolve coverage map references
-    /// to unused functions. This is necessary so unused functions will appear
-    /// as uncovered (coverage execution count `0`) in LLVM coverage reports.
-    fn define_unused_fn(&self, def_id: DefId);
-
-    /// For LLVM codegen, returns a function-specific `Value` for a global
-    /// string, to hold the function name passed to LLVM intrinsic
-    /// `instrprof.increment()`. The `Value` is only created once per instance.
-    /// Multiple invocations with the same instance return the same `Value`.
-    fn get_pgo_func_name_var(&self, instance: Instance<'tcx>) -> Self::Value;
-}
-
 pub trait CoverageInfoBuilderMethods<'tcx>: BackendTypes {
     /// Handle the MIR coverage info in a backend-specific way.
     ///

compiler/rustc_codegen_ssa/src/traits/mod.rs

@@ -33,7 +33,7 @@ pub use self::asm::{AsmBuilderMethods, AsmMethods, GlobalAsmOperandRef, InlineAs
 pub use self::backend::{Backend, BackendTypes, CodegenBackend, ExtraBackendMethods};
 pub use self::builder::{BuilderMethods, OverflowOp};
 pub use self::consts::ConstMethods;
-pub use self::coverageinfo::{CoverageInfoBuilderMethods, CoverageInfoMethods};
+pub use self::coverageinfo::CoverageInfoBuilderMethods;
 pub use self::debuginfo::{DebugInfoBuilderMethods, DebugInfoMethods};
 pub use self::declare::PreDefineMethods;
 pub use self::intrinsic::IntrinsicCallMethods;
@@ -59,7 +59,6 @@ pub trait CodegenMethods<'tcx>:
     + MiscMethods<'tcx>
     + ConstMethods<'tcx>
     + StaticMethods
-    + CoverageInfoMethods<'tcx>
     + DebugInfoMethods<'tcx>
     + AsmMethods<'tcx>
     + PreDefineMethods<'tcx>
@@ -75,7 +74,6 @@ impl<'tcx, T> CodegenMethods<'tcx> for T where
         + MiscMethods<'tcx>
         + ConstMethods<'tcx>
         + StaticMethods
-        + CoverageInfoMethods<'tcx>
         + DebugInfoMethods<'tcx>
         + AsmMethods<'tcx>
         + PreDefineMethods<'tcx>