used for _Bool is not the same as the primitive width (which for _Bool
is 1 bit). The load and store changes add some casts to make the
types consistent. The EmitLValue changes make sure that the pointer is
of an appropriate type for loading the bitfield.
This isn't perfect, but it's an improvement, and getting everything
right depends on actually laying out structs in an ABI-compliant way.
llvm-svn: 51224