cpp-utilities: build as a shared library

This is required to get some header-only definitions set up
so that applications using them export symbols properly.

pkgs/development/libraries/cpp-utilities/default.nix

@@ -22,6 +22,9 @@ stdenv.mkDerivation rec {
   buildInputs = lib.optionals stdenv.isDarwin [
     iconv # needed on Darwin, see https://github.com/Martchus/cpp-utilities/issues/4
   ];
+
+  cmakeFlags = ["-DBUILD_SHARED_LIBS=ON"];
+
   # Otherwise, tests fail since the resulting shared object libc++utilities.so is only available in PWD of the make files
   preCheck = ''
     checkFlagsArray+=(