The caller may ignore the return value (will be addressed with later
commit) so simply zero the count from the get-go. We're pretty much do
so, in all cases but one :-\
Fixes: cef12efc15 ("glamor: Implement GetSupportedModifiers")
Cc: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Cc: Daniel Stone <daniels@collabora.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>