Fix hipExtLaunchMultiKernelMultiDevice compilation issue

Fix compilation error on hip-hcc+clang , hip-vdi+clang
Enabled hipExtLaunchMultiKernelMultiDevice test on hip-vdi path
hipExtLaunchMultiKernelMultiDevice common declaration for all paths

Change-Id: I76031840614fce8e12a8e845548fa43a389a741a

tests/src/runtimeApi/module/hipExtLaunchMultiKernelMultiDevice.cpp

@@ -23,7 +23,7 @@ THE SOFTWARE.
 // single GPU or multi GPUs.
 
 /* HIT_START
- * BUILD: %t %s ../../test_common.cpp EXCLUDE_HIP_PLATFORM nvcc vdi
+ * BUILD: %t %s ../../test_common.cpp EXCLUDE_HIP_PLATFORM nvcc
  * TEST: %t
  * HIT_END
  */