qt5: Add debugging symbols in development builds

qt5 build with developerBuild do not contain debug information as
they are stripped by the qt build process.

pkgs/development/libraries/qt-5/modules/qtbase.nix

@@ -162,6 +162,8 @@ stdenv.mkDerivation {
   qtQmlPrefix = "lib/qt-${qtCompatVersion}/qml";
   qtDocPrefix = "share/doc/qt-${qtCompatVersion}";
 
+  dontStrip = developerBuild;
+
   setOutputFlags = false;
   preConfigure = ''
     export LD_LIBRARY_PATH="$PWD/lib:$PWD/plugins/platforms''${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH"
@@ -253,6 +255,7 @@ stdenv.mkDerivation {
     ++ lib.optionals developerBuild [
       "-developer-build"
       "-no-warnings-are-errors"
+      "-force-debug-info"
     ]
     ++ (
       if (!stdenv.hostPlatform.isx86_64) then [