Removed commented out code

A previous CL commented out code instead of removing it.  This CL fixes
this grave error.

Test: TH
Change-Id: I1daeaaa1ad90230aec639d603e7cdb9b61af251a

rust/project_json.go

@@ -54,7 +54,6 @@ type rustProjectCrate struct {
 }
 
 type rustProjectJson struct {
-	// Roots  []string           `json:"roots"`
 	Crates []rustProjectCrate `json:"crates"`
 }
 
@@ -248,9 +247,6 @@ func (singleton *projectGeneratorSingleton) addCrate(ctx android.SingletonContex
 	idx := len(singleton.project.Crates)
 	singleton.knownCrates[rModule.Name()] = crateInfo{Idx: idx, Deps: deps}
 	singleton.project.Crates = append(singleton.project.Crates, crate)
-	// rust-analyzer requires that all crates belong to at least one root:
-	// https://github.com/rust-analyzer/rust-analyzer/issues/4735.
-	// singleton.project.Roots = append(singleton.project.Roots, path.Dir(crate.RootModule))
 	return idx, true
 }