gh-152502: Detect the curses mouse interface and is_* methods portably (GH-152705)

gh-152502: Detect the curses mouse interface and is_* methods portably (GH-152705)

The mouse interface (getmouse(), has_mouse(), the BUTTON* constants,
window.mouse_trafo(), ...) and the window is_*() state-query methods were gated
on ncurses-specific macros, so they were dropped on other curses implementations
that provide them, such as NetBSD curses and PDCurses.

Gate them instead on configure capability probes (for functions NetBSD curses
provides, since it defines no identifying macro) or on NCURSES_EXT_FUNCS or the
PDCURSES macro (for functions only ncurses and PDCurses provide).  Probe for
getmouse() with its X/Open getmouse(MEVENT *) signature, since PDCurses declares
an incompatible getmouse(void) unless built for the ncurses mouse API, which
PDC_NCMOUSE now always selects.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>