Land rapid7#19439, Update bypassuac_comhijack supported arch

This explicitly defines x86 and x64 as supported architectures for the
bypassuac_comhijack module. Prior to this change there were no defined
architectures and if you tried to use an x64 based payload the module
would fail.

Author: jheysel-r7

modules/exploits/windows/local/bypassuac_comhijack.rb

@@ -43,6 +43,7 @@ def initialize(info = {})
           'OJ Reeves'       # MSF module
         ],
         'Platform' => ['win'],
+        'Arch' => [ ARCH_X86, ARCH_X64 ],
         'SessionTypes' => ['meterpreter'],
         'Targets' => [
           ['Automatic', {}]