Removed un-needed function overload for setting userdata

Fixed bugs in win64 impl where it did not check if the process was a known invalid value

include/uniproc.h

@@ -22,6 +22,5 @@ bool uniproc_are_processes_finished(const uniproc_process* p, const size_t num_p
 void uniproc_nullify_processes(uniproc_process* p, const size_t num_processes);
 bool uniproc_is_process_null(const uniproc_process* p);
 void uniproc_await_any_processes(const uniproc_process* p, const size_t num_processes);
-void uniproc_set_userdata(uniproc_process* p, const uint64_t userdata);
 void uniproc_set_userdata(uniproc_process* p, void const* userdata);
 void* uniproc_get_userdata(uniproc_process* p);