eina: Eina_Module - check whether the file exists or not, before memory allocation...

eina: Eina_Module - check whether the file exists or not, before memory allocation of Eina_Module

Summary:
I got an issue from emotion_basic_example, because my machine has following directories.

/usr/local/lib/emotion/modules/
├── gstreamer
│   ├── linux-gnu-i686-1.7.99
│   ├── linux-gnu-i686-1.8.0
│   └── linux-gnu-i686-1.8.99
└── gstreamer1
    ├── linux-gnu-i686-1.8.99
    └── v-1.10

The defined MODULE_ARCH is v-1.10, and the _emotion_modules which is returned by eina_module_arch_list_get(); has two items.
Because eina_module_new(); creates Eina_Module, even though the "/usr/local/lib/emotion/modules/gstreamer/v-1.10/module.so"
does not exist.

Test Plan: Create directory without MODULE_ARCH, run emotion_basic_example, and check whether it works properly or not.

Reviewers: raster, seoz, Hermet, woohyun, jpeg, cedric

Subscribers: cedric, seoz

Differential Revision: https://phab.enlightenment.org/D1200

Signed-off-by: Cedric BAIL <c.bail@partner.samsung.com>