docker: allow "cc" command to run in user context

Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>

tests/docker/docker.py

@@ -421,6 +421,8 @@ class CcCommand(SubCommand):
                             help="The docker image in which to run cc")
         parser.add_argument("--cc", default="cc",
                             help="The compiler executable to call")
+        parser.add_argument("--user",
+                            help="The user-id to run under")
         parser.add_argument("--source-path", "-s", nargs="*", dest="paths",
                             help="""Extra paths to (ro) mount into container for
                             reading sources""")
@@ -434,6 +436,8 @@ class CcCommand(SubCommand):
         if args.paths:
             for p in args.paths:
                 cmd += ["-v", "%s:%s:ro,z" % (p, p)]
+        if args.user:
+            cmd += ["-u", args.user]
         cmd += [args.image, args.cc]
         cmd += argv
         return Docker().command("run", cmd, args.quiet)