This patch renames memcmp test to memcmp_64 and adds a memcmp_32 test
for testing the 32 bits version of memcmp()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Fix 64-bit build by adding build_32bit test]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>