raise_memory_limit() earlier -- resolves OOM on 64-bit platforms

raise_memory_limit() earlier -- resolves OOM on 64-bit platforms

On 64-bit platforms the in-memory footprint of our libraries is quite a bit
larger than usual, and we hit the 8MB default memory limit before we call
raise_memory_limit(). This patch moves raise_memory_limit() and
get_realsize() to setuplib so we can call them earlier, and moves the
call to _before_ we include the libraries.

On AMD64, for MOODLE_17_STABLE the footprint is about 9.5MB. Diet time? :-)