t001_x of the struct-layout test has such beauties as:
typedef _Bool Tal16bool __attribute__((aligned (16)));
struct S49 { Tal16bool a:1; } ;. a only gets BIGGEST_ALIGNMENT (i.e. 64 bits), rather than the 128 bits
required for Tal16bool. Should we enforce that any storage element allocated
for a run of ms-bitfields get the full alignment of the basetype, even when it exceeds
the size of the basetype and of BIGGEST_ALIGNMENT?
