adb: fix erase-remove_if idiom.

This probably doesn't have any actual effect, because there should only
be one smartsocket listener so this will happen to work, but this looks
sketchy.

Test: mma
Test: adb server nodaemon & (sleep 1; adb kill-server)
Change-Id: Id00ab1fc1fc029949c675ae6e3b1a77f3e9e4c69