Use cmake features to set C++ version

Change-Id: Icf5dcd781b8fecc7a39117f3c6dee97dcba9dcca

opencl/amdocl/CMakeLists.txt

@@ -1,5 +1,8 @@
 
-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)
 
 # Some linker flags, -Wl,--unresolved-symbols=report-all being one of them, requires -shared-libasan if using -fsanitize=address.
 # If -Wl,--unresolved-symbols=report-all is removed from CMAKE_SHARED_LINKER_FLAGS, then update this snippet

opencl/tools/clinfo/CMakeLists.txt

@@ -1,4 +1,7 @@
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
 
 set (CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)