remove BOOST_NORETURN fallback

Author: grisumbras

include/boost/json/detail/config.hpp

@@ -47,26 +47,6 @@
 # endif
 #endif
 
-// BOOST_NORETURN ---------------------------------------------//
-// Macro to use before a function declaration/definition to designate
-// the function as not returning normally (i.e. with a return statement
-// or by leaving the function scope, if the function return type is void).
-#if !defined(BOOST_NORETURN)
-#  if defined(_MSC_VER)
-#    define BOOST_NORETURN __declspec(noreturn)
-#  elif defined(__GNUC__)
-#    define BOOST_NORETURN __attribute__ ((__noreturn__))
-#  elif defined(__has_attribute) && defined(__SUNPRO_CC) && (__SUNPRO_CC > 0x5130)
-#    if __has_attribute(noreturn)
-#      define BOOST_NORETURN [[noreturn]]
-#    endif
-#  elif defined(__has_cpp_attribute)
-#    if __has_cpp_attribute(noreturn)
-#      define BOOST_NORETURN [[noreturn]]
-#    endif
-#  endif
-#endif
-
 #ifndef BOOST_ASSERT
 #define BOOST_ASSERT assert
 #endif