sync.md: Update comment about unpredictable LL/SC lock clearing by a taken branch.

sync.md: Update comment about unpredictable LL/SC lock clearing by a taken branch.

	* config/alpha/sync.md: Update comment about unpredictable LL/SC lock
	clearing by a taken branch.
	(sync_<fetchop_name><mode>): Split when epilogue_completed is set,
	effectively after bbro pass.
	(sync_nand<mode>): Ditto.
	(sync_old_<fetchop_name><mode>): Ditto.
	(sync_old_nand<mode>): Ditto.
	(sync_new_<fetchop_name><mode>): Dito.
	(sync_new_nand<mode>): Ditto.
	(sync_compare_and_swap<mode>_1): Ditto.
	(*sync_compare_and_swap<mode>): Ditto.
	(sync_lock_test_and_set<mode>_1): Ditto.
	("sync_lock_test_and_set<mode>): Ditto.

From-SVN: r151115