openttd: fix build against icu-76

Without the change `openttd` build fails in `master` as
https://hydra.nixos.org/build/290760688:

    [100%] Linking CXX executable openttd
    ld: CMakeFiles/openttd_lib.dir/src/survey.cpp.o: undefined reference to symbol 'u_versionToString_76'
    ld: /nix/store/...-icu4c-76.1/lib/libicuuc.so.76: error adding symbols: DSO missing from command line
    collect2: error: ld returned 1 exit status

pkgs/games/openttd/default.nix

@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchzip,
+  fetchpatch,
   cmake,
   pkg-config,
   SDL2,
@@ -71,6 +72,16 @@ stdenv.mkDerivation rec {
     hash = "sha256-YT4IE/rJ9pnpeMWKbOra6AbSUwW19RwOKlXkxwoMeKY=";
   };
 
+  patches = [
+    # Fix build against icu-76:
+    #   https://github.com/OpenTTD/OpenTTD/pull/13048
+    (fetchpatch {
+      name = "icu-75.patch";
+      url = "https://github.com/OpenTTD/OpenTTD/commit/14fac2ad37bfb9cec56b4f9169d864f6f1c7b96e.patch";
+      hash = "sha256-L35ybnTKPO+HVP/7ZYzWM2mA+s1RAywhofSuzpy/6sc=";
+    })
+  ];
+
   nativeBuildInputs = [
     cmake
     pkg-config

pkgs/games/openttd/jgrpp.nix

@@ -10,6 +10,7 @@ openttd.overrideAttrs (oldAttrs: rec {
     rev = "jgrpp-${version}";
     hash = "sha256-aEmuwWNxqjuLmiWMrqwTUtCwdwDMA00eQspCHntxEXw=";
   };
+  patches = [];
 
   buildInputs = oldAttrs.buildInputs ++ [ zstd ];