core: always release Irq_proxy startup lock

Prior this patch the startup lock was not released if the call of
'_associate()' failed. In this condition, the caller of the constructor
was infinitely blocked.
libc_lwip: use libc's 'get-/freeaddrinfo()'

This patch reduces problems when connecting Arora to lighttpd via
nic_bridge. Patch by Christian Prochaska
core: support upgrades of init's Env:: sessions