Update rand (OsRng is now provided by rand_core and rand since 0.2.2).

4 jobs for master in 3 minutes and 35 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #20945
build:linux

00:01:04

passed #20946
build:redox

00:00:57

 
  Test
passed #20947
test:linux

00:00:58

passed #20948
test:redox

00:02:31