AArch64: Add fixes to bionic/tests

This patch adds minor fixes to the bionic unit tests.

Change-Id: Ie10f33c631ed6c10987923d678711d22931ddb05
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>
diff --git a/benchmarks/Android.mk b/benchmarks/Android.mk
index 83e490f..f64c108 100644
--- a/benchmarks/Android.mk
+++ b/benchmarks/Android.mk
@@ -27,6 +27,7 @@
     -Wall -Wextra \
     -Werror \
     -fno-builtin \
+    -std=gnu++11 \
 
 benchmark_src_files = \
     benchmark_main.cpp \