[server] fix mysql multiple id in get_emailusers
Merge pull request #62 from Chilledheart/patch-2

[server] fix mysql multiple id in get_emailusers
Fix SQL bug in get_superusers.
[build] fix bus error while execute make -jN (N>1)

 - please use latest version of seaf-codegen.py,
    at least the one in haiwen/libsearpc#17