acl_usm_test: fix GCC warning: ignoring #pragma warning

Guard suppression of MVSC unreferenced formal parameter warning.

https://github.com/intel/fpga-runtime-for-opencl/blob/aca879be71ca8f7e06a9d5bafbe5c79820bb9a3d/test/acl_command_queue_test.cpp#L4-L11

[106/113] Building CXX object test/CMakeFiles/acl_test.dir/acl_usm_test.cpp.o
../test/acl_usm_test.cpp:8:0: warning: ignoring #pragma warning  [-Wunknown-pragmas]
 #pragma warning(push, 0)

../test/acl_usm_test.cpp:10:0: warning: ignoring #pragma warning  [-Wunknown-pragmas]
 #pragma warning(pop);

Author: pcolberg

test/acl_usm_test.cpp

@@ -5,9 +5,14 @@
 // compiling for ARM
 #ifndef __arm__
 
-#pragma warning(push, 0)
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4100) // unreferenced formal parameter
+#endif
 #include <CppUTest/TestHarness.h>
-#pragma warning(pop);
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
 
 #include <CL/opencl.h>