tests: Add example of using KVM acceleration with an app

Add #ifdef's to gpu-hello.cpp demonstrating how to annotate an application
for KVM acceleration.

tests/test-progs/gpu-hello/src/gpu-hello.cpp

@@ -41,6 +41,12 @@
 #include <fstream>
 #include <string>
 
+#ifdef KVM_SWITCH
+#include "m5op.h"
+
+void *m5_mem = (void*)0xffffc90000000000;
+#endif
+
 #define SUCCESS 0
 #define FAILURE 1
 
@@ -247,6 +253,10 @@ runCLKernel(cl_kernel kernel)
         return FAILURE;
     }
 
+#ifdef KVM_SWITCH
+    m5_switchcpu();
+#endif
+
     // 2. Launch kernel
     status = clEnqueueNDRangeKernel(commandQueue, kernel, 1, NULL,
                                     globalThreads, localThreads, 0, NULL,