Compiler - set CXX Compiler if not set (#466)

[ROCm/rocdecode commit: 7a6073103a]

projects/rocdecode/samples/videoDecodeBatch/CMakeLists.txt

@@ -36,7 +36,10 @@ endif()
 
 list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/../../cmake)
 list(APPEND CMAKE_PREFIX_PATH ${ROCM_PATH}/hip ${ROCM_PATH})
-set(CMAKE_CXX_COMPILER ${ROCM_PATH}/bin/amdclang++)
+# Set AMD Clang as default compiler
+if (NOT DEFINED CMAKE_CXX_COMPILER)
+  set(CMAKE_CXX_COMPILER ${ROCM_PATH}/bin/amdclang++)
+endif()
 
 # rocDecode sample build type
 set(DEFAULT_BUILD_TYPE "Release")