gcc7: Removed X11 components, since they were only used by langJava

See also:

51ac1d8df0
https://github.com/NixOS/nixpkgs/pull/39866#discussion_r185813776

pkgs/development/compilers/gcc/7/default.nix

@@ -12,12 +12,6 @@
 , libelf                      # optional, for link-time optimizations (LTO)
 , isl ? null # optional, for the Graphite optimization framework.
 , zlib ? null
-,   pkgconfig ? null
-, gtk2 ? null, libart_lgpl ? null
-, libX11 ? null, libXt ? null, libSM ? null, libICE ? null, libXtst ? null
-, libXrender ? null, xproto ? null, renderproto ? null, xextproto ? null
-, libXrandr ? null, libXi ? null, inputproto ? null, randrproto ? null
-, x11Support ? false
 , enableMultilib ? false
 , enablePlugin ? hostPlatform == buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
@@ -65,11 +59,6 @@ let version = "7.3.0";
       })
       ++ optional langFortran ../gfortran-driving.patch;
 
-    xlibs = [
-      libX11 libXt libSM libICE libXtst libXrender libXrandr libXi
-      xproto renderproto xextproto inputproto randrproto
-    ];
-
     /* Platform flags */
     platformFlags = let
         gccArch = targetPlatform.platform.gcc.arch or null;
@@ -155,9 +144,6 @@ let version = "7.3.0";
 
 in
 
-# We need all these X libraries when building AWT with GTK+.
-assert x11Support -> (filter (x: x == null) ([ gtk2 libart_lgpl ] ++ xlibs)) == [];
-
 stdenv.mkDerivation ({
   name = crossNameAddon + "${name}${if stripped then "" else "-debug"}-${version}";