patch 9.0.1957: termcap options should change when setting keyprotocol

patch 9.0.1957: termcap options should change when setting keyprotocol

Problem:  termcap options should change on keyprotocol setting
Solution: Apply termcap entries when 'keyprotocol' changes

When the 'keyprotocol' option was set after startup (including in a
user's .vimrc) the termcap entries associated with the matching protocol
were not applied. Thus, setting the option has no affect.

When 'keyprotocol' is changed it should also update the termcap entries.

closes: #13211

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Gregory Anders <greg@gpanders.com>