maint: adjust badarguments example generation for fadvise.
maint: adjust badarguments example generation for fadvise.

* specs/posix_compat_spec.yaml (fadvise): Adjust fadvise
generation specifier.

Signed-off-by: Gary V. Vaughan <f9023000f29773649f3850298becb9544b5fd6a9@gnu.org>

ardje/luaposix,snegovick/luaposix,jimmyharris/luaposix,rrthomas/luaposix,luaposix/luaposix,ardje/luaposix,zevv/luaposix,rrthomas/luaposix,snegovick/luaposix,jimmyharris/luaposix,zevv/luaposix