exiv2: fix exiv2.pc file

This fix comes from #71669.

pkgs/development/libraries/exiv2/default.nix

@@ -26,6 +26,11 @@ stdenv.mkDerivation rec {
   cmakeFlags = [
     "-DEXIV2_BUILD_PO=ON"
     "-DEXIV2_BUILD_DOC=ON"
+    # the cmake package does not handle absolute CMAKE_INSTALL_INCLUDEDIR correctly
+    # (setting it to an absolute path causes include files to go to $out/$out/include,
+    #  because the absolute path is interpreted with root at $out).
+    "-DCMAKE_INSTALL_INCLUDEDIR=include"
+    "-DCMAKE_INSTALL_LIBDIR=lib"
   ];
 
   outputs = [ "out" "dev" "doc" "man" ];