Use on-stack bit array for tracking AI segment visits
Store kconfig labels separately
Check type of window handler function
Add typedef for newmenu subfunction
Switch manual join menu not to use nm_messagebox1

Fixes a remotely triggerable crash caused by parsing game names as a
format string.
Move -pthread to be Linux only
Switch MP abort-game menu not to use nm_messagebox1
Switch endlevel message dialog not to use nm_messagebox1
Add special case to save CPPDEFINES to configure header

Avoid cluttering the command line by moving CPPDEFINES to the configure
header.
Fix nm_messagebox usage to avoid redundant format string parse
Add type checking to nm_messagebox format string
Add type checking to newmenu subfunction userdata
Simplify setup for ui_messagebox_n