Avoid Msf::Module::Platform

We don't know how to generate an exe payload if the platform is
Msf::Module::Platform, so don't use it.

lib/msf/core/exploit/exe.rb

@@ -181,12 +181,12 @@ protected
     # Architecture shares the same load order.
 
     unless opts[:platform]
-      if self.respond_to? :payload_instance
+      if self.respond_to?(:payload_instance) && payload_instance.platform.platforms != [Msf::Module::Platform]
         opts[:platform] = payload_instance.platform
       elsif self.respond_to? :target_platform
         opts[:platform] = target_platform
       elsif self.respond_to? :platform
-       opts[:platform] = platform
+        opts[:platform] = platform
       end
     end
 
@@ -194,6 +194,7 @@ protected
       if self.respond_to? :payload_instance
         opts[:arch] = payload_instance.arch
       elsif self.respond_to? :target_arch
+        $stderr.puts "target specific arch"
         opts[:arch] = target_arch
       elsif self.respond_to? :arch
         opts[:arch] = arch