Use static memory for DB file path

Use static memory for DB file path

- Issue:
In some code, g_path and g_backup_path can be deallocated even if it
would be referenced.

- Solution:
g_path and g_backup_path should not be allocated the memory dynamically
because the life cycle of those variables are the same as the program.
So this patch changes the variables to use static memory. Through this
patch, unintended memory deallocation will be removed.

Change-Id: Idc64bc76e4cfc884770d83576923d2670e61c364
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>