scripts: update west to latest upstream version.

Update to the latest west. This includes a new 'attach' command. There
are also multi-repo commands, but those won't get exposed to the user
unless they install Zephyr using "west init" + "west fetch" (and not,
say, "git clone").

Replace the launchers; they now detect whether zephyr is part of a
multi-repo installation, and run the west code in its own repository
if that is the case.

This also requires an update to:

- the flash/debug CMakeLists.txt, as the new west package is no longer
  executable as a module and must have its main script run by the
  interpreter instead.

- the documentation, to reflect a rename and with a hack to fix
  the automodule directive in flash-debug.rst for now

Signed-off-by: Marti Bolivar <marti@foundries.io>

scripts/meta/west/runners/xtensa.py

@@ -0,0 +1,40 @@
+# Copyright (c) 2017 Linaro Limited.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+'''Runner for debugging with xt-gdb.'''
+
+from os import path
+
+from runners.core import ZephyrBinaryRunner, RunnerCaps
+
+
+class XtensaBinaryRunner(ZephyrBinaryRunner):
+    '''Runner front-end for xt-gdb.'''
+
+    def __init__(self, cfg):
+        super(XtensaBinaryRunner, self).__init__(cfg)
+
+    @classmethod
+    def name(cls):
+        return 'xtensa'
+
+    @classmethod
+    def capabilities(cls):
+        return RunnerCaps(commands={'debug'})
+
+    @classmethod
+    def do_add_parser(cls, parser):
+        parser.add_argument('--xcc-tools', required=True,
+                            help='path to XTensa tools')
+
+    @classmethod
+    def create(cls, cfg, args):
+        # Override any GDB with the one provided by the XTensa tools.
+        cfg.gdb = path.join(args.xcc_tools, 'bin', 'xt-gdb')
+        return XtensaBinaryRunner(cfg)
+
+    def do_run(self, command, **kwargs):
+        gdb_cmd = [self.cfg.gdb, self.cfg.kernel_elf]
+
+        self.check_call(gdb_cmd)