must in order for backends that do want to support large integer types to be
able to function. Consequently, don't assert if the bitwidth > 64 bits
when computing the size and alignment. Instead, compute the size by rounding
up to the next even number of bytes for the size. Compute the alignment
as the same as the LongABIAlignment. These provide reasonable defaults
that the target can override.

llvm-svn: 33943