package/fluxbox: fix build with gcc 11

Fix the following build failure with gcc 11:

util/fluxbox-remote.cc: In function 'int main(int, char**)':
util/fluxbox-remote.cc:76:32: error: ordered comparison of pointer with integer zero ('unsigned char*' and 'int')
   76 |             && text_prop.value > 0
      |                ~~~~~~~~~~~~~~~~^~~

Fixes:
 - http://autobuild.buildroot.org/results/6e718bb662aa4961ea264eb81e4b7e7b20485e30

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
(cherry picked from commit b1fce2f871)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/fluxbox/0001-fixes-bug-1138.patch

@@ -0,0 +1,25 @@
+From 22866c4d30f5b289c429c5ca88d800200db4fc4f Mon Sep 17 00:00:00 2001
+From: John Sennesael <john@aminking.com>
+Date: Mon, 2 Nov 2015 15:14:32 -0600
+Subject: [PATCH] fixes bug #1138
+
+[Retrieved from:
+https://github.com/fluxbox/fluxbox/commit/22866c4d30f5b289c429c5ca88d800200db4fc4f]
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+---
+ util/fluxbox-remote.cc | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/util/fluxbox-remote.cc b/util/fluxbox-remote.cc
+index 59852e6a..504015b5 100644
+--- a/util/fluxbox-remote.cc
++++ b/util/fluxbox-remote.cc
+@@ -73,7 +73,7 @@ int main(int argc, char **argv) {
+     if (strcmp(cmd, "result") == 0) {
+         XTextProperty text_prop;
+         if (XGetTextProperty(disp, root, &text_prop, atom_result) != 0
+-            && text_prop.value > 0
++            && text_prop.value != 0
+             && text_prop.nitems > 0) {
+ 
+             printf("%s", text_prop.value);