packages/crypto @ release-branch.go1.11

Filippo Valsorda 37a17fe027 internal/subtle: add Any/InexactOverlap (new package) and apply them across packages		%!s(int64=7) %!d(string=hai) anos
..
auth	365904b0f3 nacl/auth: use KeySize constant consistently.	%!s(int64=8) %!d(string=hai) anos
box	74b34b9dd6 all: make overlap rules wording consistent	%!s(int64=8) %!d(string=hai) anos
secretbox	37a17fe027 internal/subtle: add Any/InexactOverlap (new package) and apply them across packages	%!s(int64=7) %!d(string=hai) anos
sign	37a17fe027 internal/subtle: add Any/InexactOverlap (new package) and apply them across packages	%!s(int64=7) %!d(string=hai) anos