[C++] Set C++ standard using idiomatic approach.

Author: denizevrenci

CMakeLists.txt

@@ -44,6 +44,14 @@ if(NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose the type of build" FORCE)
 endif(NOT CMAKE_BUILD_TYPE)
 
+if(NOT DEFINED CMAKE_CXX_STANDARD)
+   set(CMAKE_CXX_STANDARD 11)
+endif()
+
+if(NOT DEFINED CMAKE_CXX_EXTENSIONS)
+   set(CMAKE_CXX_EXTENSIONS OFF)
+endif()
+
 if(SBE_TESTS)
     set(SBE_THIRDPARTY_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/thirdparty")
 
@@ -73,7 +81,7 @@ endif()
 find_package(Threads)
 
 if(UNIX)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -fexceptions -g -Wall -Wpedantic -Wextra -Wno-unused-parameter")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fexceptions -g -Wall -Wpedantic -Wextra -Wno-unused-parameter")
     set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -O0")
     set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -Ofast")
 endif()