Problem: need to check for C++ standard in cmake

Solution: use CheckCXXCompilerFlag to check for support for
-std=gnu++11

CMakeLists.txt

@@ -5,6 +5,17 @@ project (ZeroMQ)
 
 list (INSERT CMAKE_MODULE_PATH 0 "${CMAKE_SOURCE_DIR}")
 
+include(CheckCXXCompilerFlag)
+CHECK_CXX_COMPILER_FLAG("-std=gnu++11" COMPILER_SUPPORTS_CXX11)
+if(COMPILER_SUPPORTS_CXX11)
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")
+endif()
+include(CheckCCompilerFlag)
+CHECK_C_COMPILER_FLAG("-std=gnu11" COMPILER_SUPPORTS_C11)
+if(COMPILER_SUPPORTS_C11)
+	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu11")
+endif()
+
 option (WITH_OPENPGM "Build with support for OpenPGM" OFF)
 option (WITH_VMCI "Build with support for VMware VMCI socket" OFF)