rtl-optimization/105577 - RTL DSE and non-call EH

When one of the first two stages of DSE removes a throwing stmt
we have to purge dead EH edges before the DF re-analyze fires off
a fast DCE since that cannot cope with the situation.

2022-05-12  Richard Biener  <rguenther@suse.de>

	PR rtl-optimization/105577
	* dse.cc (rest_of_handle_dse): Make sure to purge dead EH
	edges before running fast DCE via df_analyze.