[unification] Move //zircon/system/utest/events to the GN build

Generated with: //scripts/unification/move_zn_element.py

scripts/unification/verify_element_move.py --reference local/initial.json:

<none>

Bug: 36139
Change-Id: Idaea41c873928dc7db4ec61313d2490236fad93e
diff --git a/build/unification/images/BUILD.gn b/build/unification/images/BUILD.gn
index a8bd1c5..881f3ef 100644
--- a/build/unification/images/BUILD.gn
+++ b/build/unification/images/BUILD.gn
@@ -594,7 +594,6 @@
     ":test.sys.elf-search-test",
     ":test.sys.ethernet-unittest",
     ":test.sys.ethertap-unittest",
-    ":test.sys.events-test",
     ":test.sys.exception-test",
     ":test.sys.fake-bti-test",
     ":test.sys.fake-mmio-reg-test",
@@ -1068,7 +1067,6 @@
     ":test.sys.elf-search-test",
     ":test.sys.ethernet-unittest",
     ":test.sys.ethertap-unittest",
-    ":test.sys.events-test",
     ":test.sys.exception-test",
     ":test.sys.fake-bti-test",
     ":test.sys.fake-mmio-reg-test",
@@ -2090,7 +2088,7 @@
     "//zircon/system/utest/ethernet:ethernet-manifest",
     #":test.sys.ethernet-unittest",
     #":test.sys.ethertap-unittest",
-    #":test.sys.events-test",
+    "//zircon/system/utest/events:events-manifest",
     #":test.sys.exception-test",
     "//zircon/system/utest/exit:exit-manifest",
     #":test.sys.fake-bti-test",
@@ -2540,7 +2538,7 @@
     "//zircon/system/utest/ethernet:ethernet-manifest",
     #":test.sys.ethernet-unittest",
     #":test.sys.ethertap-unittest",
-    #":test.sys.events-test",
+    "//zircon/system/utest/events:events-manifest",
     #":test.sys.exception-test",
     "//zircon/system/utest/exit:exit-manifest",
     #":test.sys.fake-bti-test",
diff --git a/zircon/system/utest/BUILD.gn b/zircon/system/utest/BUILD.gn
index 7b9476f..4811d4d 100644
--- a/zircon/system/utest/BUILD.gn
+++ b/zircon/system/utest/BUILD.gn
@@ -222,7 +222,6 @@
       "dlfcn",
       "dlopen-indirect-deps",
       "driver-test",
-      "events",
       "exception",
       "fidl",
       "fidl-coding-tables",
diff --git a/zircon/system/utest/events/BUILD.gn b/zircon/system/utest/events/BUILD.gn
index 44b21ec..9ef2f3c 100644
--- a/zircon/system/utest/events/BUILD.gn
+++ b/zircon/system/utest/events/BUILD.gn
@@ -2,11 +2,32 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-zx_test("events") {
+##########################################
+# Though under //zircon, this build file #
+# is meant to be used in the Fuchsia GN  #
+# build.                                 #
+# See fxb/36139.                         #
+##########################################
+
+assert(!defined(zx) || zx != "/",
+       "This file can only be used in the Fuchsia GN build.")
+
+import("//build/test.gni")
+import("//build/unification/images/migrated_manifest.gni")
+
+test("events") {
+  # Dependent manifests unfortunately cannot be marked as `testonly`.
+  # Remove when converting this file to proper GN build idioms.
+  testonly = false
+  configs += [ "//build/unification/config:zircon-migrated" ]
   sources = [ "events.c" ]
   deps = [
-    "$zx/system/ulib/fdio",
-    "$zx/system/ulib/unittest",
-    "$zx/system/ulib/zircon",
+    "//zircon/public/lib/fdio",
+    "//zircon/public/lib/unittest",
   ]
+  libs = [ "zircon" ]
+}
+
+migrated_manifest("events-manifest") {
+  deps = [ ":events" ]
 }