opts-common.c's cmdline_handle_error handles invalid arguments
for options with CL_ERR_ENUM_ARG by building a string listing the
valid arguments.  By also building a vec of valid arguments, we
can use find_closest_string and provide a hint if we see a close
misspelling.

gcc/ChangeLog:
	PR driver/69265
	* Makefile.in (GCC_OBJS): Move spellcheck.o to...
	(OBJS-libcommon-target): ...here.
	* opts-common.c: Include spellcheck.h.
	(cmdline_handle_error): Build a vec of valid options and use it
	to suggest provide hints for misspelled arguments.

gcc/testsuite/ChangeLog:
	PR driver/69265
	* gcc.dg/spellcheck-options-11.c: New test case.

From-SVN: r236439