BUILD.gn: don't build cron binary

The cron binary isn't used on Fuchsia and contains some libc calls we
may not want to support. Don't build it.

Change-Id: I336231e97cb3253fb35a6e024165e61644ce7017
diff --git a/BUILD.gn b/BUILD.gn
index a2c90b4..0ad2fbb 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -19,7 +19,7 @@
     ":cols",
     ":comm",
     ":cp",
-    ":cron",
+    # ":cron",
     ":cut",
     ":date",
     ":dirname",
@@ -163,8 +163,7 @@
 }
 sbase_util("cp") {
 }
-sbase_util("cron") {
-}
+# sbase_util("cron") {}
 sbase_util("cut") {
 }
 sbase_util("date") {
@@ -387,10 +386,6 @@
     },
 
     {
-      name = "cron"
-    },
-
-    {
       name = "cut"
     },