Include missing headers

Bug: None
Test: Build
Change-Id: Id4967af4ab48ceda10c45edcb0bc4b856b991fd6
diff --git a/bluetooth/1.0/default/hci_protocol.cc b/bluetooth/1.0/default/hci_protocol.cc
index a208da1..5d6f1d1 100644
--- a/bluetooth/1.0/default/hci_protocol.cc
+++ b/bluetooth/1.0/default/hci_protocol.cc
@@ -18,6 +18,7 @@
 
 #define LOG_TAG "android.hardware.bluetooth-hci-hci_protocol"
 #include <assert.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <log/log.h>