linux-ramdump-parser-v2: respect --nm-path and --gdb-path

Somewhere along the way we started ignoring the --nm-path and --gdb-path
options. Fix this. Also ensure that the command line options take
precedence over anything from local_settings.py or anything discovered
from CROSS_COMPILE.

Change-Id: I39ff653c7de7fb1de170701b898567c9b2356835