Lib: fix potential leak in mem_pool impl
Lib: fix potential leak in mem_pool impl

amqp_pool_alloc will leak if the initial alloc succeeds, but the alloc for the
block-list fails. This fixes that.

alanxz/rabbitmq-c,alanxz/rabbitmq-c,Haster2004/rabbitmq-c,Haster2004/rabbitmq-c,alanxz/rabbitmq-c,Haster2004/rabbitmq-c