ipa-prop: Fix multiple-target speculation resolution

ipa-prop: Fix multiple-target speculation resolution

As the FIXME which this patch removes states, the current code does
not work when a call with multiple speculative targets gets resolved
through parameter tracking during inlining - it feeds the inliner an
edge it has already dealt with.  The patch makes the code which should
prevent it aware of the possibility that that speculation can have
more than one target now.

gcc/ChangeLog:

2020-09-30  Martin Jambor  <mjambor@suse.cz>

	PR ipa/96394
	* ipa-prop.c (update_indirect_edges_after_inlining): Do not add
	resolved speculation edges to vector of new direct edges even in
	presence of multiple speculative direct edges for a single call.

gcc/testsuite/ChangeLog:

2020-09-30  Martin Jambor  <mjambor@suse.cz>

	PR ipa/96394
	* gcc.dg/tree-prof/pr96394.c: New test.