Temporary build fix

Unhook fitness from the build to work around build break in playfair. We
updated the Sky package in an incompatible way, which means we need to roll in
a new playfair package to build fitness.

examples/BUILD.gn

@@ -7,7 +7,8 @@ group("examples") {
 
   deps = [
     "//examples/demo_launcher",
-    "//examples/fitness",
+    # TODO(abarth): Add fitness back once playfair rolls
+    #"//examples/fitness",
     "//examples/game",
     "//examples/mine_digger",
     "//examples/rendering",