Use gfc_commit_symbol() to remove UNDO status instead of new function.

Use gfc_commit_symbol() to remove UNDO status instead of new function.

This is a cleaner version, removing an unneeded function and
making sure that no memory leaks can occur if callers change.

gcc/fortran/ChangeLog:

	PR fortran/119157
	* gfortran.h (gfc_pop_undo_symbol): Remove prototype.
	* interface.cc (gfc_get_formal_from_actual_arglist): Use
	gfc_commit_symbol() instead of gfc_pop_undo_symbol().
	* symbol.cc (gfc_pop_undo_symbol): Remove.