fix race condition when using ecore_main_loop_thread_safe_call_sync.
fix race condition when using ecore_main_loop_thread_safe_call_sync.

Backport from commit 30d7779178d8b961004dabae6b0ed682f6889e97
on https://git.enlightenment.org/core/efl.git

gfriloux/ecore,gfriloux/ecore,gfriloux/ecore