tree-optimization/116674 - vectorizable_simd_clone_call and re-analysis

tree-optimization/116674 - vectorizable_simd_clone_call and re-analysis

When SLP analysis scraps an instance because it fails to analyze we
can end up calling vectorizable_* in analysis mode on a node that
was analyzed during the analysis of that instance again.
vectorizable_simd_clone_call wasn't expecting that and instead
guarded analysis/transform code on populated data structures.
The following changes it so it survives re-analysis.

	PR tree-optimization/116674
	* tree-vect-stmts.cc (vectorizable_simd_clone_call): Support
	re-analysis.

	* g++.dg/vect/pr116674.cc: New testcase.