Removed trace now that interface stats are available.
Backported interface type and promiscuous INET mode options from bin/passive to bin/echo.
Fix TOPDIR-relative paths (this is TOPDIR from wanproxy's
perspective), add -lpcap to LDADD.
The assert() introduced in b8914c8 was too strong in that it forgot
completely that a watcher may be stopped by another watcher during an
event loop iteration where that watcher had no events of its own.