Don't depend on String8 cast to C string

Bug: 295394788
Test: m checkbuild
Change-Id: I6aa039b6b2a4944e3537ef133f8785890d957edd
diff --git a/tools/aapt2/DominatorTree_test.cpp b/tools/aapt2/DominatorTree_test.cpp
index a0679a6..087f456 100644
--- a/tools/aapt2/DominatorTree_test.cpp
+++ b/tools/aapt2/DominatorTree_test.cpp
@@ -50,8 +50,8 @@
  private:
   void VisitConfig(const DominatorTree::Node* node, const int indent) {
     auto config_string = node->value()->config.toString();
-    buffer_ << std::string(indent, ' ') << (config_string.empty() ? "<default>" : config_string)
-            << std::endl;
+    buffer_ << std::string(indent, ' ')
+            << (config_string.empty() ? "<default>" : config_string.c_str()) << std::endl;
   }
 
   void VisitNode(const DominatorTree::Node* node, const int indent) {