When including <test/bignum_helpers.h>, the library/ directory now needs to
be on the include path.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Move bignum-related helper functions to their own files under tests/include
and tests/src. The primary motivation is that a subsequent commit will make
bignum_helpers.h include library/bignum*.h, but we want to be able to
include <test/helpers.h> without having the library directory on the include
path (we do this in some programs under programs/ intended for testing).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
