gnu: fluxbox: Fix build.

* gnu/packages/patches/fluxbox-1.3.7-gcc.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/wm.scm (fluxbox)[source](patches): Add it.

gnu/local.mk

@@ -1153,6 +1153,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/flatpak-fix-path.patch			\
   %D%/packages/patches/flatpak-unset-gdk-pixbuf-for-sandbox.patch	\
   %D%/packages/patches/fluxbox-1.3.7-no-dynamic-cursor.patch	\
+  %D%/packages/patches/fluxbox-1.3.7-gcc.patch			\
   %D%/packages/patches/fontconfig-cache-ignore-mtime.patch	\
   %D%/packages/patches/fontforge-hurd.patch			\
   %D%/packages/patches/foobillard++-pkg-config.patch		\

gnu/packages/patches/fluxbox-1.3.7-gcc.patch

@@ -0,0 +1,16 @@
+Author: Danny Milosavljevic <dannym@scratchpost.org>
+Date: 2023-06-12
+License: expat
+
+diff -ur orig/fluxbox-1.3.7/util/fluxbox-remote.cc fluxbox-1.3.7/util/fluxbox-remote.cc
+--- orig/fluxbox-1.3.7/util/fluxbox-remote.cc	1970-01-01 01:00:01.000000000 +0100
++++ fluxbox-1.3.7/util/fluxbox-remote.cc	2023-05-01 01:11:52.225547895 +0200
+@@ -73,7 +73,7 @@
+     if (strcmp(cmd, "result") == 0) {
+         XTextProperty text_prop;
+         if (XGetTextProperty(disp, root, &text_prop, atom_result) != 0
+-            && text_prop.value > 0
++            && text_prop.value != NULL
+             && text_prop.nitems > 0) {
+ 
+             printf("%s", text_prop.value);

gnu/packages/wm.scm

@@ -1073,7 +1073,8 @@ drags, snap-to-border support, and virtual desktops.")
                (base32
                 "1h1f70y40qd225dqx937vzb4k2cz219agm1zvnjxakn5jkz7b37w"))
               (patches
-               (search-patches "fluxbox-1.3.7-no-dynamic-cursor.patch"))))
+               (search-patches "fluxbox-1.3.7-no-dynamic-cursor.patch"
+                               "fluxbox-1.3.7-gcc.patch"))))
     (build-system gnu-build-system)
     (arguments
      `(#:make-flags '("CPPFLAGS=-U__TIME__") ;ugly, but for reproducibility