gh-113565: Improve and harden detection of curses dependencies (#119816)

1. Use pkg-config to check for ncursesw/panelw. If that fails, use 
   pkg-config to check for ncurses/panel.
2. Regardless of pkg-config output, search for curses/panel headers, so
   we're sure we have all defines in pyconfig.h.
3. Regardless of pkg-config output, check if libncurses or libncursesw
   contains the 'initscr' symbol; if it does _and_ pkg-config failed
   earlier, add the resulting -llib linker option to CURSES_LIBS.
   Ditto for 'update_panels' and PANEL_LIBS.
4. Wrap the rest of the checks with WITH_SAVE_ENV and make sure we're 
   using updated LIBS and CPPFLAGS for those.

Add the PY_CHECK_CURSES convenience macro.

Author: erlend-aasland

Include/py_curses.h

@@ -36,13 +36,21 @@
 #define NCURSES_OPAQUE 0
 #endif
 
-#ifdef HAVE_NCURSES_H
-#include <ncurses.h>
-#else
-#include <curses.h>
+#if defined(HAVE_NCURSESW_NCURSES_H)
+#  include <ncursesw/ncurses.h>
+#elif defined(HAVE_NCURSESW_CURSES_H)
+#  include <ncursesw/curses.h>
+#elif defined(HAVE_NCURSES_NCURSES_H)
+#  include <ncurses/ncurses.h>
+#elif defined(HAVE_NCURSES_CURSES_H)
+#  include <ncurses/curses.h>
+#elif defined(HAVE_NCURSES_H)
+#  include <ncurses.h>
+#elif defined(HAVE_CURSES_H)
+#  include <curses.h>
 #endif
 
-#ifdef HAVE_NCURSES_H
+#ifdef NCURSES_VERSION
 /* configure was checking <curses.h>, but we will
    use <ncurses.h>, which has some or all these features. */
 #if !defined(WINDOW_HAS_FLAGS) && \

Misc/NEWS.d/next/Build/2024-06-02-13-23-26.gh-issue-113565.8xBlId.rst

@@ -0,0 +1,2 @@
+Improve :mod:`curses` and :mod:`curses.panel` dependency checks in
+:program:`configure`.

Modules/_curses_panel.c

@@ -19,7 +19,13 @@ static const char PyCursesVersion[] = "2.1";
 
 #include "py_curses.h"
 
-#include <panel.h>
+#if defined(HAVE_NCURSESW_PANEL_H)
+#  include <ncursesw/panel.h>
+#elif defined(HAVE_NCURSES_PANEL_H)
+#  include <ncurses/panel.h>
+#elif defined(HAVE_PANEL_H)
+#  include <panel.h>
+#endif
 
 typedef struct {
     PyObject *PyCursesError;

Modules/_cursesmodule.c

@@ -128,7 +128,7 @@ static const char PyCursesVersion[] = "2.2";
 #include <langinfo.h>
 #endif
 
-#if !defined(HAVE_NCURSES_H) && (defined(sgi) || defined(__sun) || defined(SCO5))
+#if !defined(NCURSES_VERSION) && (defined(sgi) || defined(__sun) || defined(SCO5))
 #define STRICT_SYSV_CURSES       /* Don't use ncurses extensions */
 typedef chtype attr_t;           /* No attr_t type is available */
 #endif