[jobs] build job-test binary for runtests

Adds a makefile for the core jobs test so that they can be run via
`runtests` as well as userboot, same as the existing thread and process
test binaries.

Test: `runtests -t job-test`
Change-Id: I3cb36a824cd45a50fd0a059bd01f776e651dc18e
diff --git a/system/utest/core/job/jobs.cpp b/system/utest/core/job/jobs.cpp
index 73121e9..a464b2b 100644
--- a/system/utest/core/job/jobs.cpp
+++ b/system/utest/core/job/jobs.cpp
@@ -445,3 +445,10 @@
 RUN_TEST(info_task_stats_fails)
 RUN_TEST(max_height_smoke)
 END_TEST_CASE(job_tests)
+
+#ifndef BUILD_COMBINED_TESTS
+int main(int argc, char** argv) {
+    bool success = unittest_run_all_tests(argc, argv);
+    return success ? 0 : -1;
+}
+#endif
diff --git a/system/utest/core/job/rules.mk b/system/utest/core/job/rules.mk
new file mode 100644
index 0000000..24434bf
--- /dev/null
+++ b/system/utest/core/job/rules.mk
@@ -0,0 +1,29 @@
+# Copyright 2019 The Fuchsia Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+LOCAL_DIR := $(GET_LOCAL_DIR)
+
+MODULE := $(LOCAL_DIR)
+
+MODULE_TYPE := usertest
+
+MODULE_USERTEST_GROUP := core
+
+MODULE_SRCS += \
+    $(LOCAL_DIR)/jobs.cpp
+
+MODULE_NAME := job-test
+
+MODULE_LIBS := \
+    system/ulib/c \
+    system/ulib/fdio \
+    system/ulib/mini-process \
+    system/ulib/unittest \
+    system/ulib/zircon
+
+MODULE_STATIC_LIBS := \
+    system/ulib/zx \
+    system/ulib/zxcpp
+
+include make/module.mk