These functions are used to simplify analysis of memory leaks in the ncurses
They are normally not available; they must be configured into the library
at build time using the --disable-leaks option.
That compiles-in code that frees memory that normally would not be freed.
Any implementation of curses must not free the memory associated with
a screen, since (even after calling endwin), it must be available
for use in the next call to refresh.
There are also chunks of memory held for performance reasons.
That makes it hard to analyze curses applications for memory leaks.
To work around this, one can build a debugging version of the ncurses
library which frees those chunks which it can, and provides these
functions to free all of the memory allocated by the ncurses library.
The _nc_free_and_exit function is the preferred one since
some of the memory which is freed may be required for the application
to continue running.
Its parameter is the code to pass to the exit routine.