oeqa: make it work for multiple users

There are failures when multiple users run oe-selftest on the same
host:

PermissionError: [Errno 13] Permission denied: '/tmp/oe-saved-
tests/201812250324_qemu'

This is because /tmp/oe-saved-tests was created by user A, while user B tries
to write data in it, then the error will happen. This patch can fix the
problem.

Move the dumped data to ${LOG_DIR}/runtime-hostdump/ rather than
/tmp/oe-saved-tests/ to fix the problem.

(From OE-Core rev: e219fe5329599cd6c3682f521eaee3852a2c8980)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/runtime/context.py

@@ -49,7 +49,6 @@ class OERuntimeTestContextExecutor(OETestContextExecutor):
     default_manifest = 'data/manifest'
     default_server_ip = '192.168.7.1'
     default_target_ip = '192.168.7.2'
-    default_host_dumper_dir = '/tmp/oe-saved-tests'
     default_extract_dir = 'packages/extracted'
 
     def register_commands(self, logger, subparsers):
@@ -71,9 +70,7 @@ class OERuntimeTestContextExecutor(OETestContextExecutor):
                 % self.default_server_ip)
 
         runtime_group.add_argument('--host-dumper-dir', action='store',
-                default=self.default_host_dumper_dir,
-                help="Directory where host status is dumped, if tests fails, default: %s" \
-                % self.default_host_dumper_dir)
+                help="Directory where host status is dumped, if tests fails")
 
         runtime_group.add_argument('--packages-manifest', action='store',
                 default=self.default_manifest,