tree-optimization/107766 - ICE with recent -ffp-contract=off fix

The following uses *node to check for FP types rather than the
child nodes which could be constant leafs and thus without a
vector type.

	PR tree-optimization/107766
	* tree-vect-slp-patterns.cc (complex_mul_pattern::matches):
	Use *node to check for FP vector types.

	* g++.dg/vect/pr107766.cc: New testcase.