Fix: Add explicit includes for assert.h and thread in sample files (#751)

* Fix: Add explicit includes for assert.h and thread in sample/vcopy.cpp

The HIP/CLR change e3cb5399c removed transitive inclusion  
of standard headers like assert.h from hip_runtime.h.  
This caused build failures in rocprof-compute samples.  

This commit explicitly includes <assert.h> and <thread>  
in vcopy.cpp to resolve potential missing definitions.  


Signed-off-by: jamessiddeley-amd <James.Siddeley@amd.com>

* Update vsequential_access.cpp

Added assert and thread imports

Signed-off-by: jamessiddeley-amd <James.Siddeley@amd.com>

* Update vrandom_access.cpp

Added assert import

Signed-off-by: jamessiddeley-amd <James.Siddeley@amd.com>

* Update vsequential_access.cpp

Signed-off-by: jamessiddeley-amd <James.Siddeley@amd.com>

---------

Signed-off-by: jamessiddeley-amd <James.Siddeley@amd.com>

sample/vsequential_access.cpp

@@ -31,6 +31,7 @@ An example code to execute sequential access to explore cache hits/misses in L2
 
 #include <hip/hip_runtime.h>
 #include <iostream>
+#include <assert.h>
 
 #define HIP_ASSERT(x) (assert((x)==hipSuccess))