build: Improve "-ltinfo" detection in configure

Since "-lncurses" might require explicit "-ltinfo" flag to link
(especially for static libncurses without libtool or pkg-config),
"-ltinfo" needs to be checked alongside "-lncurses" and not after it.

Signed-off-by: Kang-Che Sung <explorer09@gmail.com>

Author: Explorer09

configure.ac

@@ -450,20 +450,39 @@ htop_check_curses_capability () {
    # At this point we have not checked the name of curses header, so
    # use forward declaration for the linking tests below.
 
-   # htop calls refresh(), which might be implemented as a macro.
-   # It is more reliable to test linking with doupdate(), which
-   # refresh() would call internally.
-   AC_MSG_CHECKING([for doupdate in $htop_msg_linker_flags])
+   # htop uses keypad() and "stdscr", but for ncurses implementation,
+   # the symbols are in "-ltinfo" and not "-lncurses".
+   # Check "-ltinfo" symbols first, as libncurses might require
+   # explicit "-ltinfo" to link (for internal dependency).
+   AC_MSG_CHECKING([for keypad in $htop_msg_linker_flags])
    AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-int doupdate(void);
+/* extern WINDOW* stdscr; */
+/* int keypad(WINDOW* win, bool enable); */
+extern void* stdscr;
+int keypad(void* win, int enable);
       ]], [[
-doupdate();
+keypad(stdscr, 0);
       ]])],
-      [AC_MSG_RESULT(yes)
-      htop_curses_capability=nonwide],
+      [AC_MSG_RESULT(yes)],
       [AC_MSG_RESULT(no)
       htop_curses_status=1])
 
+   # htop calls refresh(), which might be implemented as a macro.
+   # It is more reliable to test linking with doupdate(), which
+   # refresh() would call internally.
+   if test "$htop_curses_status" -eq 0; then
+      AC_MSG_CHECKING([for doupdate in $htop_msg_linker_flags])
+      AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+int doupdate(void);
+         ]], [[
+doupdate();
+         ]])],
+         [AC_MSG_RESULT(yes)
+         htop_curses_capability=nonwide],
+         [AC_MSG_RESULT(no)
+         htop_curses_status=1])
+   fi
+
    if test "x$htop_curses_status$enable_unicode" = x0yes; then
       AC_MSG_CHECKING([for mvadd_wchnstr in $htop_msg_linker_flags])
       AC_LINK_IFELSE([AC_LANG_PROGRAM([[
@@ -553,6 +572,15 @@ none-*|nonwide-yes)
       if htop_check_curses_capability "" "-l$curses_name"; then
          break
       fi
+      # For ncurses implementation, an extra "-ltinfo" or "-ltinfow"
+      # flag might be needed to link.
+      if test "x$enable_unicode" = xyes &&
+         htop_check_curses_capability "" "-l$curses_name -ltinfow"; then
+         break
+      fi
+      if htop_check_curses_capability "" "-l$curses_name -ltinfo"; then
+         break
+      fi
    done
    ;;
 esac
@@ -579,10 +607,6 @@ if test "x$enable_unicode" = xyes; then
       [AC_CHECK_HEADERS([ncurses/term.h], [],
          [AC_CHECK_HEADERS([term.h], [],
             [AC_MSG_ERROR([can not find required term header file])])])])
-
-   # check if additional linker flags are needed for keypad(3)
-   # (at this point we already link against a working ncurses library with wide character support)
-   AC_SEARCH_LIBS([keypad], [tinfow tinfo])
 else
    AC_CHECK_HEADERS([curses.h], [],
       [AC_CHECK_HEADERS([ncurses/curses.h], [],
@@ -593,10 +617,6 @@ else
    AC_CHECK_HEADERS([ncurses/term.h], [],
       [AC_CHECK_HEADERS([term.h], [],
          [AC_MSG_ERROR([can not find required term header file])])])
-
-   # check if additional linker flags are needed for keypad(3)
-   # (at this point we already link against a working ncurses library)
-   AC_SEARCH_LIBS([keypad], [tinfo])
 fi
 CFLAGS=$htop_save_CFLAGS