Support tagged module references

There are cases where a module needs to refer to an intermediate
output of another module instead of its final output.  For example,
a module may want to use the .jar containing .class files from
another module whose final output is a .jar containing classes.dex
files.  Support a new ":module{.tag}" format in any property that
is annotated with `android:"path"`, which will query the target
module for its ".tag" output(s).

Test: path_properties_test.go, paths_test.go
Test: no unexpected changes in build.ninja
Change-Id: Icd3c9b0d83ff125771767c04046fcffb9fc3f65a

android/path_properties.go

@@ -39,14 +39,12 @@ func pathDepsMutator(ctx BottomUpMutatorContext) {
 		pathProperties := pathPropertiesForPropertyStruct(ctx, ps)
 		pathProperties = FirstUniqueStrings(pathProperties)
 
-		var deps []string
 		for _, s := range pathProperties {
-			if m := SrcIsModule(s); m != "" {
-				deps = append(deps, m)
+			if m, t := SrcIsModuleWithTag(s); m != "" {
+				ctx.AddDependency(ctx.Module(), sourceOrOutputDepTag(t), m)
 			}
 		}
 
-		ctx.AddDependency(ctx.Module(), SourceDepTag, deps...)
 	}
 }