Update soong for blueprint change to allow multiple deps

Blueprint allows multiple dependencies on the same module after
https://github.com/google/blueprint/pull/210.

Fix defaults, WalkDeps can now find the same defaults module multiple
times.

Fix droiddoc, if the srcs_lib points to a lib module that is
specified multiple times, for example through explicit properties
and implicit default libraries, the srcs would be listed on the
command line multiple times.  Move srcs_lib to use its own dependency
tag.

Test: m checkbuild
Change-Id: Ia30ce83be1382820d76bca5046ad18cbffe8af1a

android/defaults.go

@@ -131,11 +131,16 @@ func defaultsDepsMutator(ctx BottomUpMutatorContext) {
 func defaultsMutator(ctx TopDownMutatorContext) {
 	if defaultable, ok := ctx.Module().(Defaultable); ok && len(defaultable.defaults().Defaults) > 0 {
 		var defaultsList []Defaults
+		seen := make(map[Defaults]bool)
+
 		ctx.WalkDeps(func(module, parent Module) bool {
 			if ctx.OtherModuleDependencyTag(module) == DefaultsDepTag {
 				if defaults, ok := module.(Defaults); ok {
-					defaultsList = append(defaultsList, defaults)
-					return len(defaults.defaults().Defaults) > 0
+					if !seen[defaults] {
+						seen[defaults] = true
+						defaultsList = append(defaultsList, defaults)
+						return len(defaults.defaults().Defaults) > 0
+					}
 				} else {
 					ctx.PropertyErrorf("defaults", "module %s is not an defaults module",
 						ctx.OtherModuleName(module))