- 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

Revert previous change in favor of a fix to the actual dtrace
libraries that addresses a #pragma issue.

Remove dependency code that caused a double inclusion.

Pointed out by: rpaulo and others

Initial commit of an I/O provider for DTrace on FreeBSD.

These probes are most useful when looking into the structures
they provide, which are listed in io.d. For example:

dtrace -n 'io:genunix::start { printf("%d\n", args[0]->bio_bcount); }'

Note that the I/O systems in FreeBSD and Solaris/Illumos are sufficiently
different that there is not a 1:1 mapping from scripts that work
with one to the other.
MFC after: 1 month

Add DTrace's io.d, which handles tranlsations for file, buffer and
device info structures as well as the fds[] array. This is a raw
version of the file, unmodified, to be used as a baseline.