e_ipc: fix creation of IPC server when $DISPLAY is a path
e_ipc: fix creation of IPC server when $DISPLAY is a path

Summary:
Some implementations of the X server (e.g. Xquartz) define their $DISPLAY
as a path. Since ecore_ipc_server_add() does not create non-existant
directories, and since it may not worth to hide the socket in a complex
path, this patch aims at reducing the $DISPLAY by only keeping its basename.

Reviewers: zmike

Subscribers: cedric

Differential Revision: https://phab.enlightenment.org/D2465

rvandegrift/e,rvandegrift/e,rvandegrift/e