pythonPackages.pybind11: apply patch to properly get headers directories

It seems as the `pybind11` build code returns the Python headers
directory (where the `pybind11` headers are stored as well on traditional
setups) rather than returning the dedicated prefix[1].

An exemplary fallout is the broken build of `pyopencl`[2].

[1] https://github.com/pybind/pybind11/issues/1425
[2] https://github.com/NixOS/nixpkgs/pull/56082

(cherry picked from commit 94c3ac2574)

pkgs/development/python-modules/pybind11/default.nix

@@ -1,4 +1,4 @@
-{ lib, buildPythonPackage, fetchPypi }:
+{ lib, buildPythonPackage, fetchPypi, fetchpatch }:
 
 buildPythonPackage rec {
   pname = "pybind11";
@@ -9,6 +9,13 @@ buildPythonPackage rec {
     sha256 = "1kz1z2cg3q901q9spkdhksmcfiskaghzmbb9ivr5mva856yvnak4";
   };
 
+  patches = [
+    (fetchpatch {
+      url = https://github.com/pybind/pybind11/commit/44a40dd61e5178985cfb1150cf05e6bfcec73042.patch;
+      sha256 = "047nzyfsihswdva96hwchnp4gj2mlbiqvmkdnhxrfi9sji8x31ka";
+    })
+  ];
+
   # Current PyPi version does not include test suite
   doCheck = false;