DO NOT MERGE: Sensor multi HAL

Squashed commit of:

Move sensors multi HAL to libhardware

Added a SensorEventQueue, a circular buffer meant for reading with one thread
and polling a subhal with another. The writing thread gets access to pointers
in the internal buffer. This design avoids a memcpy on write when the multihal
fetches subhal events using poll().

Unit-tests include multithreaded reading and writing lots of events, in
random-sized chunks.

This is not used by the multihal yet. That will be a different CL.

MultiHal multithreaded polling

Tests SensorEventQueue I/O when the queue is full.
Reduced debug logging in multihal.

deactivated multihal logspam, made warnings warnings, left critical startup info

Removed unneeded linux/input.h includes, to fix Mac SDK build

Change-Id: I1e35508949df98a1acef7a4a2d012eea87b4a5eb
diff --git a/modules/sensors/Android.mk b/modules/sensors/Android.mk
new file mode 100644
index 0000000..5b787d4
--- /dev/null
+++ b/modules/sensors/Android.mk
@@ -0,0 +1,52 @@
+#
+# Copyright (C) 2013 The Android Open-Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+LOCAL_PATH := $(call my-dir)
+
+ifeq ($(USE_SENSOR_MULTI_HAL),true)
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := sensors.$(TARGET_DEVICE)
+
+LOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)/hw
+
+LOCAL_CFLAGS := -DLOG_TAG=\"MultiHal\"
+
+LOCAL_SRC_FILES := \
+    multihal.cpp \
+    SensorEventQueue.h \
+    SensorEventQueue.cpp \
+
+LOCAL_SHARED_LIBRARIES := \
+    libcutils \
+    libdl \
+    liblog \
+    libstlport \
+    libutils \
+
+LOCAL_PRELINK_MODULE := false
+LOCAL_STRIP_MODULE := false
+
+LOCAL_C_INCLUDES := \
+    external/stlport/stlport \
+    bionic \
+
+include $(BUILD_SHARED_LIBRARY)
+
+endif # USE_SENSOR_MULTI_HAL
+
+include $(call all-subdir-makefiles)