Remove redundant declaration of __cxa_allocate_exception
Fixes
@@ -16,8 +16,6 @@ int eh_trampoline();
uint64_t cxx_exception_class;
-extern "C" void *__cxa_allocate_exception(size_t) noexcept;
-
/**
* Our own definitions of C++ ABI functions and types. These are provided
* because this file must not include cxxabi.h. We need to handle subtly
