adb: make ctrl-c when spawning a daemon not kill the daemon.

Previously, using ctrl-c in a command that needs to spawn a daemon
because one isn't already available would kill the daemon along with the
foreground process.

Bug: http://b/26982628
Change-Id: I7fefc531c3e4895423e7b466322b5426d01dc9ef
(cherry picked from commit b72b3f8c92a0b2d4377d5bec15eb45869b8711ac)
1 file changed