builtins.c (expand_builtin_va_arg): Give warnings not errors for promoted argument types; build trap.

        * builtins.c (expand_builtin_va_arg): Give warnings not errors for
        promoted argument types; build trap.
        (expand_builtin_trap): New.
        (expand_builtin): Use it.
        * stmt.c (expand_nl_goto_receivers): Likewise.
        * expr.h (expand_builtin_trap): Declare.
        * libfuncs.h (LTI_abort, abort_libfunc): New.
        * optabs.c (init_optabs): Init abort_libfunc.

        * gcc.dg/va-arg-1.c: Expect warnings, not errors.

From-SVN: r51643