Fix #14951: FP unreadVariable with function pointer member #20539

Job	Run time
build_cmake (ubuntu:24.04, true, true)	2m 58s
build_cmake (alpine:3.23, false, false)	4m 29s
build_make (ubuntu:25.10)	3m 20s
build_make (ubuntu:24.04)	3m 2s
build_make (alpine:3.23)	6m 11s
build_cmake (ubuntu:25.10, true, true)	3m 13s
	23m 13s

Provide feedback