Port [] alarm management to GRPC.

This change implements a platform independent alarm manager in alarm.c.
It's integrated with iomgr, and some tests are cleaned up.

The alarm implementation itself is a fairly direct port of LazyAlarmList from eventmanager.
SpinLock has been replaced for now with gpr_mu, and other atomic operations have been dropped (again, for now).
A majority of tests have been ported.
	Change on 2014/12/19 by ctiller <ctiller@google.com>
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82551363
diff --git a/src/core/iomgr/alarm_internal.h b/src/core/iomgr/alarm_internal.h
new file mode 100644
index 0000000..e605ff8
--- /dev/null
+++ b/src/core/iomgr/alarm_internal.h
@@ -0,0 +1,50 @@
+/*
+ *
+ * Copyright 2014, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef __GRPC_INTERNAL_IOMGR_ALARM_INTERNAL_H_
+#define __GRPC_INTERNAL_IOMGR_ALARM_INTERNAL_H_
+
+/* iomgr internal api for dealing with alarms */
+
+int grpc_alarm_check(gpr_timespec now);
+
+void grpc_alarm_list_init(gpr_timespec now);
+void grpc_alarm_list_shutdown();
+
+gpr_timespec grpc_alarm_list_next_timeout();
+
+/* the following must be implemented by each iomgr implementation */
+
+void grpc_kick_poller();
+
+#endif /* __GRPC_INTERNAL_IOMGR_ALARM_INTERNAL_H_ */