Update GN to version 533454

Change-Id: I484eb051a648cf4ef43b6ac3c697647e204abaa4
diff --git a/fuchsia.ensure b/fuchsia.ensure
index 434aaa4..0a705dc 100644
--- a/fuchsia.ensure
+++ b/fuchsia.ensure
@@ -12,8 +12,7 @@
 infra/ninja/${platform} version:1.8.2
 
 # GN
-infra/tools/gn/${os=linux}-${arch} gn_version:507254
-infra/tools/gn/${os=mac}-${arch} gn_version:499403
+infra/tools/gn/${platform} gn_version:533454
 
 # godepfile
 fuchsia/tools/godepfile/${platform} git_revision:6922d7833617841e853a0be52a285f6cd07a0a10