wic: Add argv argument to main

Make it possible to call wic as an API from tests passing
command line parameters as arguments to main.

This is yet another enabler for wic unit testing.

(From OE-Core rev: 8cb9ac3751424d429a38f6f80d733b289b6684ea)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/wic

@@ -279,13 +279,13 @@ def start_logging(loglevel):
     logging.basicConfig(filname='wic.log', filemode='w', level=loglevel)
 
 
-def main():
+def main(argv):
     parser = optparse.OptionParser(version="wic version %s" % __version__,
                                    usage=wic_usage)
 
     parser.disable_interspersed_args()
 
-    (options, args) = parser.parse_args()
+    (options, args) = parser.parse_args(argv)
 
     if len(args):
         if args[0] == "help":
@@ -298,7 +298,7 @@ def main():
 
 if __name__ == "__main__":
     try:
-        ret = main()
+        ret = main(sys.argv[1:])
     except Exception:
         ret = 1
         import traceback