treewide: get rid of osx cmake flags

Flags that we now set globally:

- CMAKE_OSX_SYSROOT
- CMAKE_OSX_DEPLOYMENT_TARGET

can now be removed.

(cherry picked from commit 8742d5de30dfe2447c0fb56a2e7410b402effc80)

pkgs/development/libraries/pcl/default.nix

@@ -29,7 +29,6 @@ stdenv.mkDerivation rec {
 
     ++ stdenv.lib.optionals stdenv.isDarwin [ Cocoa AGL cf-private ];
   cmakeFlags = stdenv.lib.optionals stdenv.isDarwin [
-    "-DCMAKE_OSX_SYSROOT=" "-DCMAKE_OSX_DEPLOYMENT_TARGET="
     "-DOPENGL_INCLUDE_DIR=${OpenGL}/Library/Frameworks"
   ];