- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Use '%zu' and '%zd' as appropriate for size_t / ssize_t.

Small regression test tool to generate two forms of ENOSPC on a file
system: out of blocks, and out of inodes. Useful for exercising the
uprintf(9) calls in UFS/ext2fs in order to detect races.