BUG/MINOR: Fix the sending function in Lua's cosocket

This is a regression from the commit a73e59b6901a164d19b1145e8511602d9814f28f.

When data are sent from a cosocket, the action is done in the context of the
applet running a lua stack and not in the context of the applet owning the
cosocket. So we must take care, explicitly, that this last applet have a buffer
(the req buffer of the cosocket).

This patch must be backported in 1.7
1 file changed