nios2: Fix up nios2_setup_incoming_varargs [PR114175]
Like for x86-64, alpha or rs6000, nios2 seems to be affected too.
Just visually checked differences in c23-stdarg-9.c assembly in a cross
without/with the patch, committed to trunk.
2024-03-20 Jakub Jelinek <jakub@redhat.com>
PR target/114175
* config/nios2/nios2.cc (nios2_setup_incoming_varargs): Only skip
nios2_function_arg_advance for TYPE_NO_NAMED_ARGS_STDARG_P functions
if arg.type is NULL.