Add dump prints when execute_fixup_cfg removes a write only var store.

Add dump prints when execute_fixup_cfg removes a write only var store.

While debugging PR 102703, I found it was hard to figure out where
the store was being removed as there was no pass which was outputting
why the store was removed.
This adds to execute_fixup_cfg the output.
Also note most of removals happen when execute_fixup_cfg is called
from the inliner.

gcc/ChangeLog:

	* tree-cfg.c (execute_fixup_cfg): Output when the statement
	is removed when it is a write only var.