Add new AndroidModuleContext helper functions

Add Host(), Device(), and Debug() to AndroidModuleContext to allow
build rule generators to easily determine build options.

Change-Id: Ib93a462cb45189399063f641b3a8df175db0592e
diff --git a/common/arch.go b/common/arch.go
index 8cc3b10..a43aa72 100644
--- a/common/arch.go
+++ b/common/arch.go
@@ -15,12 +15,13 @@
 package common
 
 import (
-	"github.com/google/blueprint"
-	"github.com/google/blueprint/proptools"
 	"fmt"
 	"reflect"
 	"runtime"
 	"strings"
+
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/proptools"
 )
 
 var (