fix for musl libc: avoid huge stack allocation
fix for musl libc: avoid huge stack allocation

too used to thread stacks being several megabytes, maybe :) The crawlerstats
gets a bit big so do a normal memory allocation for it. seems to work, but I
can't run tests on musl without making the debug binary build.

guikcd/memcached,dormando/memcached,memcached/memcached,dormando/memcached,gencer/memcached,dormando/memcached,gencer/memcached,dormando/memcached,memcached/memcached,gencer/memcached,memcached/memcached,memcached/memcached,gencer/memcached,guikcd/memcached,gencer/memcached,guikcd/memcached,dormando/memcached,guikcd/memcached,guikcd/memcached,memcached/memcached