_Static_assert is new in C11, and older versions of GCC don't support
it. Detect whether static_assert is available in <assert.h> and if not,
define a fallback macro.
Change-Id: Iaf513677e5f356832e0a3d1f6b1f4f9ea07e6627
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
