Cygwin support: Prefix symbol name with _ when gcc defsym option used
Cygwin support: Prefix symbol name with _ when gcc defsym option used

  - With gcc on Cygwin, symbol names luaopen_xxx are prefixed by _ char.
  When defsym gcc option is used to redefine symbol, prefix symbol names with _

lcheylus/haka,lcheylus/haka,lcheylus/haka