HPCC-14724 Add -stdlib=libc++ to CXXFLAGS

This flag is needed for OS X version before 10.9.0

cmake_modules/commonSetup.cmake

@@ -284,7 +284,7 @@ IF ("${COMMONSETUP_DONE}" STREQUAL "")
       endif ()
     endif ()
     if (CMAKE_COMPILER_IS_CLANGXX)
-      SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror=logical-op-parentheses -Werror=bool-conversions -Werror=return-type -Werror=comment")
+      SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++ -Werror=logical-op-parentheses -Werror=bool-conversions -Werror=return-type -Werror=comment")
       SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}  -Werror=bitwise-op-parentheses -Werror=tautological-compare")
       SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}  -Wno-switch-enum -Wno-format-zero-length -Wno-switch")
       SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}  -Qunused-arguments")  # Silence messages about pthread not being used when linking...