Fix windows Meterpreter clipboard manipulation access denied errors

[adfoster-r7]

Fixes an intermittent issue with Windows Meterpreter which caused 'Access Denied' errors when Meterpreter attempte to get or set the clipboard data when either the user or another application was also manipulating the clipboard

Pulls in metasploit-payloads:

• Update extapi OpenClipboard to support retrying if acquiring the lock failed - Update extapi OpenClipboard to support retrying if acquiring the lock failed metasploit-payloads#666
• Fix broken readme code snippets - Fix broken readme code snippets metasploit-payloads#664

Verification

• Verify the same steps as Update extapi OpenClipboard to support retrying if acquiring the lock failed metasploit-payloads#666

[dwelch-r7]

Release Notes

Fixes an intermittent issue with Windows Meterpreter which caused 'Access Denied' errors when Meterpreter attempted to get or set the clipboard data when either the user or another application was also manipulating the clipboard