xmlstarlet: fix build with clang 16

Fixes an incompatible function pointer error when building with clang 16.

pkgs/tools/text/xml/xmlstarlet/default.nix

@@ -12,6 +12,11 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [ pkg-config ];
   buildInputs = [ libxml2 libxslt ];
 
+  patches = [
+    # Fixes an incompatible function pointer error with clang 16.
+    ./fix-incompatible-function-pointer.patch
+  ];
+
   preConfigure =
     ''
       export LIBXSLT_PREFIX=${libxslt.dev}

pkgs/tools/text/xml/xmlstarlet/fix-incompatible-function-pointer.patch

@@ -0,0 +1,11 @@
+--- a/src/xml_elem.c	2012-08-12 09:18:59.000000000 -0600
++++ b/src/xml_elem.c	2023-07-11 13:17:14.220809280 -0600
+@@ -186,7 +186,7 @@
+  * put @name into @data->array[@data->offset]
+  */
+ static void
+-hash_key_put(void *payload, void *data, xmlChar *name)
++hash_key_put(void *payload, void *data, const xmlChar *name)
+ {
+     ArrayDest *dest = data;
+     dest->array[dest->offset++] = name;