Support performance tests

Support performance tests while direct tests commands keep unchanged.
To build performance tests, run "make build_perf".
To run all performance testis, run "make perf".
To run specific tests, for example, run
/usr/bin/ctest -C performance -R performance_tests/perfDispatch --verbose
To run individual test, for example, run
performance_tests/memory/hipPerfMemMallocCpyFree

Change-Id: I168c1b9ef1ec21b392d48648d0c71e8fbd37d57b

perftests/perfDispatch/timer.h

@@ -0,0 +1,28 @@
+#ifndef _TIMER_H_
+#define _TIMER_H_
+
+#ifdef _WIN32
+typedef __int64 i64 ;
+#endif
+#ifdef __linux__
+typedef long long i64;
+#endif
+
+class CPerfCounter {
+
+public:
+    CPerfCounter();
+    ~CPerfCounter();
+    void Start(void);
+    void Stop(void);
+    void Reset(void);
+    double GetElapsedTime(void);
+
+private:
+
+    i64 _freq;
+    i64 _clocks;
+    i64 _start;
+};
+
+#endif // _TIMER_H_