[test][async-loop] Relocate unit tests to exist alongside source

Change-Id: I572c24dbcaf13e0197037499e379f94956cc5aa7

zircon/system/utest/async-loop/BUILD.gn → zircon/system/ulib/async-loop/test/BUILD.gn

@@ -2,6 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+group("test") {
+  testonly = true
+  deps = [
+    ":async-loop",
+  ]
+}
+
 test("async-loop") {
   sources = [
     "loop_tests.cpp",

zircon/system/utest/BUILD.gn

@@ -53,6 +53,7 @@ if (current_cpu != "") {
       "$zx/system/uapp/disk-pave:install-disk-image-test",
       "$zx/system/uapp/nand-util:nand-util-test",
       "$zx/system/ulib/async/test",
+      "$zx/system/ulib/async-loop/test",
       "$zx/system/ulib/blobfs/test",
       "$zx/system/ulib/bootfs:bootfs-test",
       "$zx/system/ulib/c:tests",
@@ -76,7 +77,6 @@ if (current_cpu != "") {
       "$zx/system/ulib/zbi-bootfs/test:test",
       "$zx/system/ulib/zxtest/test",
       "abigen",
-      "async-loop",
       "async-testutils",
       "backtrace-request",
       "biotime",