Start separaration of staging_buffer.cpp code.

Still #include staging_buffer.cpp into hip_hcc.cpp.
Directed tests compile hip_hcc to static library and use the library.

include/hcc_detail/staging_buffer.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include "hsa.h"
+
+struct ihipDevice_t;
+
+//-------------------------------------------------------------------------------------------------
+struct StagingBuffer {
+
+    static const int _max_buffers = 4;
+
+    StagingBuffer(ihipDevice_t *device, size_t bufferSize, int numBuffers) ;
+    ~StagingBuffer();
+
+    void CopyHostToDevice(void* dst, const void* src, size_t sizeBytes, hsa_signal_t *waitFor);
+    void CopyHostToDevicePinInPlace(void* dst, const void* src, size_t sizeBytes, hsa_signal_t *waitFor);
+
+    void CopyDeviceToHost   (void* dst, const void* src, size_t sizeBytes, hsa_signal_t *waitFor);
+    void CopyDeviceToHostPinInPlace(void* dst, const void* src, size_t sizeBytes, hsa_signal_t *waitFor);
+
+
+private:
+    ihipDevice_t    *_device;
+    size_t          _bufferSize;  // Size of the buffers.
+    int             _numBuffers;
+
+    char            *_pinnedStagingBuffer[_max_buffers];
+    hsa_signal_t     _completion_signal[_max_buffers];
+};