[env_fuchsia] fix includes and dependencies

Missing dependencies were causing random build failures. This change
makes them explicit, and removes an unnecessary include.

Test: builds after running fx build-zircon on an empty out dir
Change-Id: If75a4d0cfeb96ff3154cda166ea2ea8509256d9e
diff --git a/BUILD.gn b/BUILD.gn
index 91a12ed..66be935 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -137,6 +137,9 @@
     "//third_party/re2",
     "//third_party/snappy",
     "//zircon/public/fidl/fuchsia-io",
+    "//zircon/public/lib/async",
+    "//zircon/public/lib/fdio",
+    "//zircon/public/lib/fit",
     "//zircon/public/lib/zx",
   ]
 
diff --git a/util/env_fuchsia.cc b/util/env_fuchsia.cc
index 547a18d..7f6689b 100644
--- a/util/env_fuchsia.cc
+++ b/util/env_fuchsia.cc
@@ -46,7 +46,6 @@
 #include <vector>
 
 #include <fuchsia/io/cpp/fidl.h>
-#include <fuchsia/sys/cpp/fidl.h>
 #include <lib/async/cpp/task.h>
 #include <lib/fdio/vfs.h>
 #include <lib/fit/defer.h>