Fixed clang build error for libgui

Fixed the order of the statements in ANDROID_SINGLETON_STATIC_INSTANCE
macro so that the templated static member variable initialization
comes before the instantiation of the Singleton class. This
fixes the clang compile error.

Change-Id: Ic47d17e152b657f2dff3191ccc3770753fdf002b
Author: Tareq A. Siraj <tareq.a.siraj@intel.com>
Reviewed-by: Edwin Vane <edwin.vane@intel.com>