Revert "add crate_root property to rust modules"

Revert submission 2605644-rulebuilder-ninja-vars

Reason for revert: b/299568218

Reverted changes: /q/submissionid:2605644-rulebuilder-ninja-vars

Change-Id: I17645fcff117909c09a016157235805f0974340b

rust/compiler.go

@@ -73,15 +73,6 @@ type BaseCompilerProperties struct {
 	// If no source file is defined, a single generated source module can be defined to be used as the main source.
 	Srcs []string `android:"path,arch_variant"`
 
-	// Entry point that is passed to rustc to begin the compilation. E.g. main.rs or lib.rs.
-	// When this property is set,
-	//    * sandboxing is enabled for this module, and
-	//    * the srcs attribute is interpreted as a list of all source files potentially
-	//          used in compilation, including the entrypoint, and
-	//    * compile_data can be used to add additional files used in compilation that
-	//          not directly used as source files.
-	Crate_root *string `android:"path,arch_variant"`
-
 	// name of the lint set that should be used to validate this module.
 	//
 	// Possible values are "default" (for using a sensible set of lints
@@ -520,8 +511,6 @@ func srcPathFromModuleSrcs(ctx ModuleContext, srcs []string) (android.Path, andr
 		ctx.PropertyErrorf("srcs", "only a single generated source module can be defined without a main source file.")
 	}
 
-	// TODO: b/297264540 - once all modules are sandboxed, we need to select the proper
-	// entry point file from Srcs rather than taking the first one
 	paths := android.PathsForModuleSrc(ctx, srcs)
 	return paths[srcIndex], paths[1:]
 }