dump_breakpad_symbols.py should have an option to keep going on error

Prior to going parallel in IMPALA-11511, the dump_breakpad_symbols.py logic kept going through the list of binaries even if one failed:

  for binary in enumerate_binaries(args):
    if not process_binary(dump_syms, binary, args.dest_dir):
      status = 1

IMPALA-11511 changed this to bail out if any dump_syms invocation failed. It might be useful to have a flag to allow the old behavior of continue past errors from dump_syms.