Pass SOCK_CLOEXEC to adb socket.

We were not passing CLOEXEC to the adb-socket in adbconnection. This
could lead to extra (unusable) jdwp PIDs in adb jdwp in some
circumstances.

Test: Build an app with wrap.sh.
      adb jdwp on a userdebug device.
      Ensure pid of wrap.sh is not present in list.
Bug: 109505014

Change-Id: Icd41bf037666d6abe35897681aed98b00fb290ac