mumps: headers remove symlink to subdir

With the upstream patch to casadi (https://github.com/casadi/casadi/pull/3899),
There is no need for nixpkgs#mumps to symlink header files to subdir mumps.
Nix packagers should manualy specify the include directory and link libraries for
the coinmumps required project like nipxkgs#libopt.

pkgs/by-name/ca/casadi/package.nix

@@ -10,6 +10,7 @@
   cplex,
   fatrop,
   fetchFromGitHub,
+  fetchpatch,
   gurobi,
   highs,
   hpipm,
@@ -45,6 +46,14 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-Mft0qhjdAbU82RgjYuKue5p7EqbTbt3ii5yXSsCFHrQ=";
   };
 
+  patches = [
+    (fetchpatch {
+      name = "fix-FindMUMPS.cmake.patch";
+      url = "https://github.com/casadi/casadi/pull/3899/commits/274f4b23f73e60c5302bec0479fe1e92682b63d2.patch";
+      hash = "sha256-3GWEWlN8dKLD6htpnOQLChldcT3hE09JWLeuCfAhY+4=";
+    })
+  ];
+
   postPatch =
     ''
       # fix case of hpipmConfig.cmake
@@ -57,11 +66,6 @@ stdenv.mkDerivation (finalAttrs: {
         '$'{CLANG_LLVM_LIB_DIR} \
         ${llvmPackages_17.libclang.lib}/lib
 
-      # fix mumps lib name. No idea where this comes from.
-      substituteInPlace cmake/FindMUMPS.cmake --replace-fail \
-        "mumps_seq" \
-        "mumps"
-
       # help casadi find its own libs
       substituteInPlace casadi/core/casadi_os.cpp --replace-fail \
         "std::vector<std::string> search_paths;" \

pkgs/by-name/mu/mumps/package.nix

@@ -51,7 +51,6 @@ stdenv.mkDerivation (finalAttrs: {
     install -Dm 444 -t $out/include/mumps_seq libseq/*.h
 
     # Add some compatibility with coin-or-mumps
-    ln -s $out/include $out/include/mumps
     ln -s $out/include/mumps_seq/mpi.h $out/include/mumps_mpi.h
   '';