Fix APR format strings for use on 64 bit systems

APR's implementation of format strings does not support %llu on 64 bit systems.
But apparently using %lu works equally well without any need for type casts.

Also APR's implementation does not support %p properly. Up to now we resorted
to using %x and casting the pointer to an unsigned int. On 64 bit systems would
only output 32 bit of the pointer address. This is fixed by using %pp
(apparently the APR replacement for %p).

Fixes #2