Add init_rc as a property to the debuggable product_variable.

Bug: 37110010
Test: See related change - verified manually that the default init_rc
file as well as the 'debuggable' init_rc file were executed.

Change-Id: Id6a51201cf10633e9a86d2c76a3e64b50225bf55

android/variable.go

@@ -65,6 +65,7 @@ type variableProperties struct {
 		Debuggable struct {
 			Cflags   []string
 			Cppflags []string
+			Init_rc  []string
 		}
 
 		// eng is true for -eng builds, and can be used to turn on additionaly heavyweight debugging