Allow modules to be enabled/disabled depending on whether APEXes are flattened.

am: 2879d41a98

Change-Id: I4ec408f99805b5229f926163fea2ebefb8515032

android/variable.go

@@ -115,6 +115,10 @@ type variableProperties struct {
 			Static_libs  []string
 			Srcs         []string
 		}
+
+		Flatten_apex struct {
+			Enabled *bool
+		}
 	} `android:"arch_variant"`
 }