popplerQt4: force linking to poppler_glib

to fix:
ldd /nix/store/...poppler-qt4-0.22.3/lib/libpoppler-qt4.so
libpoppler.so.36 => not found

pkgs/development/libraries/poppler/default.nix

@@ -65,6 +65,7 @@ in rec {
   poppler_qt4 = poppler_drv "qt4" {
     propagatedBuildInputs = [ qt4 poppler_glib ];
     patches = qtcairo_patches;
+    NIX_LDFLAGS = "-lpoppler";
     postConfigure = "cd qt4";
   };
 }