Declare a const variable for tizenglobalapp uid

Declare a const variable for tizenglobalapp uid

GLOBAL_USER is defined other package's header file.
To clarify, declare tizenglobalapp uid as const variable itself and
use this variable.

Change-Id: I36f800fa1876274242dffffdca50acf6b3524ff3
Signed-off-by: Sangyoon Jang <s89.jang@samsung.com>