pidgin: disable gtkspell

gtkspell is optional, and is being removed from Nixpkgs due to its
dependence on GTK 2.

pkgs/applications/networking/instant-messengers/pidgin/default.nix

@@ -13,7 +13,6 @@
   gst_all_1,
   gtk2,
   gtk2-x11,
-  gtkspell2,
   intltool,
   lib,
   libice,
@@ -94,7 +93,6 @@ let
       ]
       ++ lib.optionals stdenv.hostPlatform.isLinux [
         gtk2
-        gtkspell2
         farstream
       ]
       ++ lib.optional stdenv.hostPlatform.isDarwin gtk2-x11;
@@ -126,16 +124,14 @@ let
       "--disable-nm"
       "--disable-tcl"
       "--disable-gevolution"
+      "--disable-gtkspell"
     ]
     ++ lib.optionals withCyrus_sasl [ "--enable-cyrus-sasl=yes" ]
     ++ lib.optionals withGnutls [
       "--enable-gnutls=yes"
       "--enable-nss=no"
     ]
-    ++ lib.optionals stdenv.hostPlatform.isDarwin [
-      "--disable-gtkspell"
-      "--disable-vv"
-    ]
+    ++ lib.optionals stdenv.hostPlatform.isDarwin [ "--disable-vv" ]
     ++ lib.optionals stdenv.cc.isClang [ "CFLAGS=-Wno-error=int-conversion" ];
 
     enableParallelBuilding = true;