jdwp: switch to SOCK_SEQPACKET.

When sending the process's PID to adbd, we use
TEMP_FAILURE_RETRY(send(...)), and check if the result is non-negative.
However, this could theoretically return short, leaving adbd waiting
for the rest of the PID. Switch the socket to a SOCK_SEQPACKET to
sidestep all of this.

Bug: http://b/36411868
Test: adb jdwp
Change-Id: I0ec75912ac579868f77554e3c6db23c7ab95a34c