c++: Fix a typo in function name

I've noticed I've made a typo in the name of the function.
Fixed thusly.

2022-11-15  Jakub Jelinek  <jakub@redhat.com>

	* cp-tree.h (next_common_initial_seqence): Rename to ...
	(next_common_initial_sequence): ... this.
	* typeck.cc (next_common_initial_seqence): Rename to ...
	(next_common_initial_sequence): ... this.
	(layout_compatible_type_p): Call next_common_initial_sequence
	rather than next_common_initial_seqence.
	* semantics.cc (is_corresponding_member_aggr): Likewise.