Use cmake features to set c++ version

Change-Id: I2649cdca5bc68298371f770a7a624a21db3f4137


[ROCm/clr commit: d4a447967e]

projects/clr/rocclr/CMakeLists.txt

@@ -55,7 +55,10 @@ find_package(ROCR REQUIRED)
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 find_package(Threads REQUIRED)
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -fPIC")
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
 add_definitions(-DLINUX -D__x86_64__ -D__AMD64__ -DUNIX_OS -DqLittleEndian -DOPENCL_MAJOR=2 -DOPENCL_MINOR=1 -DCL_TARGET_OPENCL_VERSION=220 -DWITH_AQL -DWITH_ONLINE_COMPILER -DATI_OS_LINUX -DATI_ARCH_X86 -DLITTLEENDIAN_CPU -DATI_BITS_64 -DATI_COMP_GCC -DWITH_TARGET_AMDGCN -DOPENCL_EXPORTS -DCL_USE_DEPRECATED_OPENCL_1_0_APIS -DCL_USE_DEPRECATED_OPENCL_1_1_APIS -DCL_USE_DEPRECATED_OPENCL_1_2_APIS -DCL_USE_DEPRECATED_OPENCL_2_0_APIS -DVEGA10_ONLY=false -DWITH_LIGHTNING_COMPILER)
 add_definitions(-DOPENCL_C_MAJOR=2 -DOPENCL_C_MINOR=0)