[3.15] gh-152502: Detect the curses mouse interface portably (GH-152705) (GH-152707)

[3.15] gh-152502: Detect the curses mouse interface portably (GH-152705) (GH-152707)

The mouse interface (getmouse(), the BUTTON* constants, ...) was gated on the
ncurses-specific NCURSES_MOUSE_VERSION macro, so it was dropped on other curses
implementations that provide it, such as NetBSD curses and PDCurses.

Gate it instead on a configure capability probe or the PDCURSES macro.  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.

(cherry picked from commit 7bbea4f4868ef89b07b986d7a0d4b585e8271f27)

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