Add -std=gnu++11 to test cflags

(cherry picked from commit 5f68087efe0476f15b0df8c78ac7e31689ec0121)

Change-Id: I6fc0d3673391654aa72e1e6bd98f4a8469c79868
diff --git a/liblog/tests/Android.mk b/liblog/tests/Android.mk
index 255dc2e..cd1bf33 100644
--- a/liblog/tests/Android.mk
+++ b/liblog/tests/Android.mk
@@ -59,7 +59,8 @@
     -g \
     -Wall -Wextra \
     -Werror \
-    -fno-builtin
+    -fno-builtin \
+    -std=gnu++11
 
 test_src_files := \
     liblog_test.cpp