meson: avoid unused arguments of main() in compiler tests

meson: avoid unused arguments of main() in compiler tests

meson.build has one test where "main" is declared unnecessarily
with argc and argv arguments, but does not use them.  Because
the test needs -Werror too, HAVE_BROKEN_SIZE_MAX is defined
incorrectly.

Fix the test and, for consistency, remove argc and argv whenever
they are not needed.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>