Typo fixes - functoin -> function [PR93796]

2020-02-18  Jakub Jelinek  <jakub@redhat.com>

	PR driver/93796
	* params.opt (-param=ipa-max-switch-predicate-bounds=): Fix help
	typo, functoin -> function.
	* tree.c (free_lang_data_in_decl): Fix comment typo,
	functoin -> function.
	* ipa-visibility.c (cgraph_externally_visible_p): Likewise.