Enable HAVE_MONOTONIC_CLOCK compiler flag

This will make D-Bus use monotonic clock instead of system time
for timeout calculation, which prevents issues when system time
changes while there is a pending call.

Bug: 25159392
TEST=Manual test on Brillo boards

Change-Id: I2f4f1ea4848b47efe10b56efe02b2c7c9b33f779

dbus/Android.mk

@@ -70,6 +70,7 @@ LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/..
 LOCAL_CFLAGS+= \
 	-DDBUS_COMPILATION \
 	-DANDROID_MANAGED_SOCKET \
+	-DHAVE_MONOTONIC_CLOCK \
 	-DDBUS_MACHINE_UUID_FILE=\"/etc/machine-id\" \
 	-DDBUS_SYSTEM_CONFIG_FILE=\"/system/etc/dbus.conf\" \
 	-DDBUS_SESSION_CONFIG_FILE=\"/system/etc/session.conf\" \