Reorganize the structure of the builds of aesce.c and sha256ce.c with
various configurations of AES/SHA256 acceleration. Now everything in a given
configuration is grouped together (building the object file, and checking
the presence or absence of certain instructions in the assembly).
Fix several instances of copypasta in -m options where we were sometimes not
allowing the compiler to use optional instructions even though we use them
in inline assembly, and sometimes allowing the compiler to use optional
instructions even though we then checked their absence
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>