CMakeLists - Fix CXX Std (#145)

[ROCm/rocjpeg commit: 40ac43a457]

projects/rocjpeg/samples/jpegDecode/CMakeLists.txt

@@ -32,14 +32,15 @@ else()
   set(ROCM_PATH /opt/rocm CACHE PATH "Default ROCm installation path")
 endif()
 # Set AMD Clang as default compiler
-if (NOT DEFINED CMAKE_CXX_COMPILER)
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED On)
+set(CMAKE_CXX_EXTENSIONS ON)
+if(NOT DEFINED CMAKE_CXX_COMPILER)
   set(CMAKE_C_COMPILER ${ROCM_PATH}/bin/amdclang)
   set(CMAKE_CXX_COMPILER ${ROCM_PATH}/bin/amdclang++)
 endif()
 
 project(jpegdecode)
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED On)
 
 list(APPEND CMAKE_PREFIX_PATH ${ROCM_PATH}/lib/cmake)