This patch adds the ability to print sizes in either units of 10^3 (SI)
or 2^10 (Binary) units.  It rounds up to three significant figures and
can be used for either memory or storage capacities.

Oh, and I'm fully aware that 64 bits is only 16EiB ... the Zetta and
Yotta units are added for future proofing against the day we have 128
bit computers ...

[fujita.tomonori@lab.ntt.co.jp: fix missed unsigned long long cast]
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>