Adjust libunwindstack MapInfo API

Test: m debuggerd_test
Change-Id: I63a2379bad3ace4755ae48bf0a83eaa0070f9077
diff --git a/debuggerd/libdebuggerd/test/UnwinderMock.h b/debuggerd/libdebuggerd/test/UnwinderMock.h
index 44a9214..8f84346 100644
--- a/debuggerd/libdebuggerd/test/UnwinderMock.h
+++ b/debuggerd/libdebuggerd/test/UnwinderMock.h
@@ -33,8 +33,7 @@
   void MockSetBuildID(uint64_t offset, const std::string& build_id) {
     unwindstack::MapInfo* map_info = GetMaps()->Find(offset);
     if (map_info != nullptr) {
-      std::string* new_build_id = new std::string(build_id);
-      map_info->build_id = new_build_id;
+      map_info->SetBuildID(std::string(build_id));
     }
   }
 };