fix Failure scoping (needed for libraries) for psexec

[busterb]

This adds the explicit path to MSF::Exploit::Failure so that we do use the wrong scope when resolving the failure class. Fixes #11627

Verification

• Start msfconsole
• use exploit/windows/smb/psexec
• Configure the module, and start a Windows 10 VM
• While the VM is booting, run psexec against it over and over.
• Verify You see various errors that are caught by the exception code, that show real failures due to the VM target not being fully booted yet.
• Verify we don't see any internal Ruby-related failures

[*] Started reverse TCP handler on 192.168.56.1:4444 
[*] 192.168.56.102:445 - Connecting to the server...
[*] 192.168.56.102:445 - Authenticating to 192.168.56.102:445 as user 'bcook'...
[*] 192.168.56.102:445 - Selecting PowerShell target
[*] 192.168.56.102:445 - Executing the payload...
[-] 192.168.56.102:445 - Unable to remove the service, ERROR_CODE: 1053
[-] 192.168.56.102:445 - Exploit aborted due to failure: unknown: 192.168.56.102:445 - Unable to execute specified command: Expecting SMB2 protocol with command=9, got SMB2 protocol with command=8
[*] Exploit completed, but no session was created.
msf5 exploit(windows/smb/psexec) > run

[*] Started reverse TCP handler on 192.168.56.1:4444 
[*] 192.168.56.102:445 - Connecting to the server...
[*] 192.168.56.102:445 - Authenticating to 192.168.56.102:445 as user 'bcook'...
[*] 192.168.56.102:445 - Selecting PowerShell target
[*] 192.168.56.102:445 - Executing the payload...
[-] 192.168.56.102:445 - Exploit aborted due to failure: unknown: 192.168.56.102:445 - Unable to execute specified command: Not a valid SMB packet
[*] Exploit completed, but no session was created.
msf5 exploit(windows/smb/psexec) > run

[*] Started reverse TCP handler on 192.168.56.1:4444 
[*] 192.168.56.102:445 - Connecting to the server...
[*] 192.168.56.102:445 - Authenticating to 192.168.56.102:445 as user 'bcook'...
[*] 192.168.56.102:445 - Selecting PowerShell target
[*] 192.168.56.102:445 - Executing the payload...
[+] 192.168.56.102:445 - Service start timed out, OK if running a command or non-service executable...
[*] Sending stage (179779 bytes) to 192.168.56.102
[*] Meterpreter session 1 opened (192.168.56.1:4444 -> 192.168.56.102:58937) at 2019-04-08 10:03:01 -0500

meterpreter >

[wvu]

LGTM.

[busterb]

Release Notes

This fix resolves an issue that caused exceptions to not be handled correctly when there is a failure to use psexec against a target.