Fix thinko in early bail out in tree-switch-conversion.

2019-09-02  Martin Liska  <mliska@suse.cz>

	* tree-switch-conversion.c (jump_table_cluster::find_jump_tables):
	Bail out when we'll end up with the same number of clusters as
	at the beginning.
	(bit_test_cluster::find_bit_tests): Likewise for bit tests.
	(jump_table_cluster::can_be_handled): Remove the guard
	as it's already handled in ::is_enabled.  Allocate output
	after early bail out.

From-SVN: r275293