In order to allow extensions being registered at fixed opcodes,
there need to be a reserved slot range. Thus `NumExtensions` needs
to start out with the upper ceiling of the reserved slot space.
Thus it cannot tell whether the array already had been allocated,
and some slots now may be NULL, so we need some extra checks.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Enrico Weigelt, metux IT consult