Merge pull request #28508 from juliendehos/eigen3

eigen: fix configuration file for pkg-config

pkgs/development/libraries/eigen/3.3.nix

@@ -14,6 +14,10 @@ stdenv.mkDerivation {
   
   nativeBuildInputs = [ cmake ];
 
+  postInstall = ''
+    sed -e '/Cflags:/s@''${prefix}/@@' -i "$out"/share/pkgconfig/eigen3.pc
+  '';
+   
   meta = with stdenv.lib; {
     description = "C++ template library for linear algebra: vectors, matrices, and related algorithms";
     license = licenses.lgpl3Plus;