ecore: Fix Asan stack overflow warning

ecore: Fix Asan stack overflow warning

Summary:
As argument can be passed by register (depending on the compiler optimization)
when we take the adress of the nbytes and pass it to send() function which reades
4 bytes from it ASAN flags it as a stack overflow . So just assign the value to a
local variable to avoid the warning.

Reviewers: Hermet

Reviewed By: Hermet

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D11914