BUG/MINOR: hlua/action: incorrect message on E_YIELD error

BUG/MINOR: hlua/action: incorrect message on E_YIELD error

When hlua_action error messages were reworked in d5b073cf1
("MINOR: lua: Improve error message"), an error was made for the
E_YIELD case.

Indeed, everywhere E_YIELD error is handled: "yield is not allowed" or
similar error message is reported to the user. But instead we currently
have: "aborting Lua processing on expired timeout".

It is quite misleading because this error message often refers to the
HLUA_E_ETMOUT case.

Thus, we now report the proper error message thanks to this patch.

This should be backported to all stable versions.
[on 2.0, the patch needs to be slightly adapted]