Cache the result of inotify check in configure

Wrap AC_LINK_IFELSE() in AC_CACHE_CHECK() to skip it if the result is
already cached.

configure

@@ -1028,6 +1028,7 @@ infodir
 docdir
 oldincludedir
 includedir
+runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -1454,6 +1455,7 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
+runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1706,6 +1708,15 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
+  -runstatedir | --runstatedir | --runstatedi | --runstated \
+  | --runstate | --runstat | --runsta | --runst | --runs \
+  | --run | --ru | --r)
+    ac_prev=runstatedir ;;
+  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
+  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
+  | --run=* | --ru=* | --r=*)
+    runstatedir=$ac_optarg ;;
+
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1843,7 +1854,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir
+		libdir localedir mandir runstatedir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1996,6 +2007,7 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
+  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -32969,6 +32981,9 @@ if test "$wxUSE_FSWATCHER" = "yes"; then
         if test "$wxUSE_UNIX" = "yes"; then
                                                 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether inotify is usable" >&5
 $as_echo_n "checking whether inotify is usable... " >&6; }
+if ${wx_cv_inotify_usable+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 int main() { return inotify_init(); }
@@ -32982,6 +32997,8 @@ else
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
+
+fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $wx_cv_inotify_usable" >&5
 $as_echo "$wx_cv_inotify_usable" >&6; }
             if test "$wx_cv_inotify_usable" = "no"; then

configure.in

@@ -5479,13 +5479,15 @@ if test "$wxUSE_FSWATCHER" = "yes"; then
             dnl inotify header may be present from a compatibility library so
             dnl check that the function is usable. We don't try to link with,
             dnl e.g. -linotify so native kqueue support is used in preference.
-            AC_MSG_CHECKING([whether inotify is usable])
+            AC_CACHE_CHECK(
+                [whether inotify is usable],
+                wx_cv_inotify_usable,
                 AC_LINK_IFELSE(
                     [AC_LANG_SOURCE([int main() { return inotify_init(); }])],
                     [wx_cv_inotify_usable=yes; AC_DEFINE(wxHAS_INOTIFY) ],
                     [wx_cv_inotify_usable=no]
                 )
-            AC_MSG_RESULT($wx_cv_inotify_usable)
+            )
             if test "$wx_cv_inotify_usable" = "no"; then
                 AC_CHECK_HEADERS(sys/event.h,,, [AC_INCLUDES_DEFAULT()])
                 if test "$ac_cv_header_sys_event_h" = "yes"; then