Revert "remove rust deps on clang prebuilts"

Revert submission 2758566

Reason for revert: b/301463284

Reverted changes: /q/submissionid:2758566

Change-Id: I54f0ecbbd922deb23009ca89ff79689e128f4f31
diff --git a/rust/rust.go b/rust/rust.go
index 26e3ffc..6d6b55e 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -472,6 +472,13 @@
 	// Paths to generated source files
 	SrcDeps          android.Paths
 	srcProviderFiles android.Paths
+
+	// Paths to specific build tools
+	Rustc         android.Path
+	Clang         android.Path
+	Llvm_ar       android.Path
+	Clippy_driver android.Path
+	Rustdoc       android.Path
 }
 
 type RustLibraries []RustLibrary
@@ -1473,9 +1480,18 @@
 				depPaths.BuildToolDeps = append(depPaths.BuildToolDeps, buildTool.Deps...)
 				switch android.RemoveOptionalPrebuiltPrefix(dep.Name()) {
 				case "rustc":
+					depPaths.Rustc = buildTool.Src
 					// rustc expects the standard cc toolchain libraries (libdl, libm, libc, etc.)
 					// not to be under the __SBOX_SANDBOX_DIR__/ directory
 					depPaths.BuildToolSrcDeps = append(depPaths.BuildToolSrcDeps, buildTool.Deps...)
+				case "clang++":
+					depPaths.Clang = buildTool.Src
+				case "llvm-ar":
+					depPaths.Llvm_ar = buildTool.Src
+				case "clippy-driver":
+					depPaths.Clippy_driver = buildTool.Src
+				case "rustdoc":
+					depPaths.Rustdoc = buildTool.Src
 				}
 			case depTag == cc.CrtBeginDepTag:
 				depPaths.CrtBegin = append(depPaths.CrtBegin, android.OutputFileForModule(ctx, dep, ""))
@@ -1596,6 +1612,13 @@
 	}
 
 	ctx.AddFarVariationDependencies([]blueprint.Variation{}, buildToolDepTag, "rustc")
+	ctx.AddFarVariationDependencies([]blueprint.Variation{}, buildToolDepTag, "clippy-driver")
+	ctx.AddFarVariationDependencies([]blueprint.Variation{}, buildToolDepTag, "rustdoc")
+	ctx.AddFarVariationDependencies([]blueprint.Variation{}, buildToolDepTag, "clang++")
+	ctx.AddFarVariationDependencies([]blueprint.Variation{}, buildToolDepTag, "clang++.real")
+	ctx.AddFarVariationDependencies([]blueprint.Variation{}, buildToolDepTag, "lld")
+	ctx.AddFarVariationDependencies([]blueprint.Variation{}, buildToolDepTag, "ld.lld")
+	ctx.AddFarVariationDependencies([]blueprint.Variation{}, buildToolDepTag, "llvm-ar")
 
 	// rlibs
 	rlibDepVariations = append(rlibDepVariations, blueprint.Variation{Mutator: "rust_libraries", Variation: rlibVariation})