tmux: add proposed upstream fix for split-window regression

In tmux 3.4, a regression was introduced that breaks the deprecated (but still
supported for backwards compatibility) -p option to split-window. Several
external tools (for example fzf.kak, fzf-tmux and nnn) break due to this. Add
the proposed upstream fix from tmux/tmux#3840.

pkgs/tools/misc/tmux/default.nix

@@ -1,6 +1,7 @@
 { lib
 , stdenv
 , fetchFromGitHub
+, fetchpatch
 , autoreconfHook
 , bison
 , libevent
@@ -37,6 +38,11 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-RX3RZ0Mcyda7C7im1r4QgUxTnp95nfpGgQ2HRxr0s64=";
   };
 
+  patches = [(fetchpatch {
+    url = "https://github.com/tmux/tmux/commit/2d1afa0e62a24aa7c53ce4fb6f1e35e29d01a904.diff";
+    hash = "sha256-mDt5wy570qrUc0clGa3GhZFTKgL0sfnQcWJEJBKAbKs=";
+  })];
+
   nativeBuildInputs = [
     pkg-config
     autoreconfHook