wayland: Simplify cross build

Now that we have a pkg-config wrapper, we can get build-time deps via
pkg-config.

pkgs/development/libraries/wayland/default.nix

@@ -23,16 +23,17 @@ in stdenv.mkDerivation rec {
 
   mesonFlags = [ "-Ddocumentation=${lib.boolToString withDocumentation}" ];
 
-  patches = lib.optional isCross ./fix-wayland-cross-compilation.patch;
-
   postPatch = lib.optionalString withDocumentation ''
     patchShebangs doc/doxygen/gen-doxygen.py
-  '' + lib.optionalString isCross ''
     substituteInPlace egl/meson.build --replace \
       "find_program('nm').path()" \
       "find_program('${stdenv.cc.targetPrefix}nm').path()"
   '';
 
+  depsBuildBuild = [
+    pkgconfig
+  ];
+
   nativeBuildInputs = [
     meson pkgconfig ninja
   ] ++ lib.optionals isCross [

pkgs/development/libraries/wayland/fix-wayland-cross-compilation.patch

@@ -1,14 +0,0 @@
-diff --git a/src/meson.build b/src/meson.build
-index 3e8c9bf..75241cb 100644
---- a/src/meson.build
-+++ b/src/meson.build
-@@ -55,8 +55,7 @@ pkgconfig.generate(
- )
- 
- if meson.is_cross_build()
--	scanner_dep = dependency('wayland-scanner', native: true, version: '>=1.14.0')
--	wayland_scanner_for_build = find_program(scanner_dep.get_pkgconfig_variable('wayland_scanner'))
-+	wayland_scanner_for_build = find_program('wayland-scanner', native: true, version: '>=1.14.0')
- else
- 	wayland_scanner_for_build = wayland_scanner
- endif