simple_queue: request more memory for items

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
memory_pool: normalize anonymous memory allocations

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
tests: add a queue test that performs many operations

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>