Implement `host_required` and `target_required` properties.

They are counterparts of LOCAL_HOST_REQUIRED_MODULES and
LOCAL_TARGET_REQUIRED_MODULES respectively.

Fixes: 128693436
Test: treehugger, convert cts/hostsidetests/devicepolicy/Android.bp
Change-Id: Id66ffca6edffe18993ac51e8930f1d0e78178249
diff --git a/android/variable.go b/android/variable.go
index 21af31f..68a24ab 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -85,10 +85,12 @@
 		// are used for dogfooding and performance testing, and should be as similar to user builds
 		// as possible.
 		Debuggable struct {
-			Cflags   []string
-			Cppflags []string
-			Init_rc  []string
-			Required []string
+			Cflags          []string
+			Cppflags        []string
+			Init_rc         []string
+			Required        []string
+			Host_required   []string
+			Target_required []string
 		}
 
 		// eng is true for -eng builds, and can be used to turn on additionaly heavyweight debugging