libcutils : reboot mount fix

On aries for eg, cache needs to be rw for the RECOVERY_PRE_COMMAND to
work because we write to /cache/.startrecovery

This patchset moves the RECOVERY_PRE_COMMAND prior to the remount.

Conflicts:
	libcutils/android_reboot.c

Change-Id: I4bd97517e00cdd117191d29b610e9623ad7d9255