Update import paths for changes to blueprint

Blueprint has been modified to include a canonical import path,
update soong to match.

Change-Id: If29d31afbf3bf2e6364961a66456fa5f8f738455
diff --git a/cc/cc.go b/cc/cc.go
index 4627440..dd1a9a6 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -19,8 +19,8 @@
 // is handled in builder.go
 
 import (
-	"blueprint"
-	"blueprint/pathtools"
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/pathtools"
 	"fmt"
 	"path/filepath"
 	"strings"