Fix x64 dll/service creation

Redo @todb-r7 Exploit::EXE fixes without additional baggage:

Using the spec https://github.com/todb-r7/metasploit-framework/blob/46d5cfc58cfcbc258cd9ce78a9322743836ca181/spec/lib/msf/core/exploit/exe_spec.rb we get the following results:

```
Msf::Exploit::EXE ..*....

Pending:
  Msf::Exploit::EXE can generate a 32-bit/64-bit payload exe
    # Need to figure out how to build the opts right (SeeRM #8367)
    # ./spec/lib/msf/core/exploit/exe_spec.rb:26

Finished in 3.01 seconds
7 examples, 0 failures, 1 pending

Coverage report generated for RSpec to /root/git/metasploit-framework/coverage. 14535 / 95710 LOC (15.19%) covered.
```