webkitgtk: ignore gettext when cross compiling

Unfortunately, CMake looks in CMAKE_PREFIX_PATH for binaries when
cross-compiling. This means that it will use gettext from
CMAKE_PREFIX_PATH even when we provide a gettext binary in PATH! This
is bad because the on in CMAKE_PREFIX_PATH is for the cross system,
not the native one. The only documented way I can find to change this
behavior is by manually setting the CMAKE_IGNORE_PATH variable.

pkgs/development/libraries/webkitgtk/default.nix

@@ -51,6 +51,7 @@
 , xdg-dbus-proxy
 , substituteAll
 , gnome3
+, glib
 }:
 
 assert enableGeoLocation -> geoclue2 != null;
@@ -78,6 +79,14 @@ stdenv.mkDerivation rec {
     ./libglvnd-headers.patch
   ];
 
+  preConfigure = stdenv.lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
+    # Ignore gettext in cmake_prefix_path so that find_program doesn't
+    # pick up the wrong gettext. TODO: Find a better solution for
+    # this, maybe make cmake not look up executables in
+    # CMAKE_PREFIX_PATH.
+    cmakeFlags+=" -DCMAKE_IGNORE_PATH=${getBin gettext}/bin"
+  '';
+
   nativeBuildInputs = [
     bison
     cmake
@@ -89,6 +98,8 @@ stdenv.mkDerivation rec {
     pkgconfig
     python3
     ruby
+    glib
+    wayland
   ];
 
   buildInputs = [