gdbclient: use host ip when connecting to gdb

When the device is not on localhost, gdbclient won't connect to it
properly.  If the serial is a tcp address, parse the host and pass that
to gdb-remote.

Bug: 228371506
Test: gdbclient.py -r /system/bin/ls /bin
Change-Id: I635d4bdc483a66ab908f5aa02aa94e2504976a45
1 file changed