MFH: r260483, r260484, r260594, r260595, r260596, r260597

Improve error message shown to the user when trying to load a module that is
already loaded or compiled withing the kernel
Point the user to dmesg(1) to get informations about why loading a module did fail
instead of printing the cryptic "Exec format error"
Update the BUGS section of kld(4) according the recent changes in kldload(8)
MFC	r260014, r260099:

gcc: Add support for label attributes and "unavailable" attribute.

Apple GCC has extensions to support for both label attributes and
an "unavailable" attribute. These are critical for objc but are
also useful in regular C/C++.

Obtained from:	Apple GCC 4.2 - 5531
MFC r260833:

Bring back r226403, the fix for bin/161526, which was (accidentally?)
reverted in r238896.

PR:		bin/161526
Reported by:	Karli.Sjoberg slu.se
MFC	r260332;
gcc: backport some fixes from llvm-gcc

llvm-gcc backported some patches from gcc trunk:

http://gcc.gnu.org/ml/gcc-cvs/2007-05/msg00662.html
http://gcc.gnu.org/ml/gcc-cvs/2007-07/msg00019.html
http://gcc.gnu.org/ml/gcc-cvs/2007-08/msg00240.html
http://gcc.gnu.org/ml/gcc-cvs/2007-08/msg00493.html

The first two were always GPL2. The last two were
added after the GPL3 transition, but were written
by aaw@google.com and Rafael Espíndola got permission
to relicense them under the GPL2 for inclusion in
llvm-gcc.

This fixes GCC-PR c++/31749

Obtained from:	llvm-gcc (rev. 75463; GPLv2)
MFC r260782:

-h and -H options backwards in manual page.
MFC r254970 (by ken):
If a drive returns ASC/ASCQ 0x04,0x11 "Logical unit not ready,
notify (enable spinup) required", instead of doing the normal
retries, poll for a change in status.

We will poll every half second for a minute for the status to
change.

Hitachi drives (and likely other SAS drives) return that ASC/ASCQ
when they are waiting to spin up.  What it means is that they are
waiting for the SAS expander to send them the SAS
NOTIFY (ENABLE SPINUP) primitive.

That primitive is the mechanism expanders/enclosures use to
sequence drive spinup to avoid overloading power supplies.
MFC r255307 (by bryanv):
Add camcontrol support for the SCSI sanitize command
MFC r256836:
Remove hard limit on number of BIOs handled with one ATA TRIM request.
MFC r256895:
Fix memory and references leak due to unfreed path.
MFC r256995:
Remove 128KB bzero() call done for every block I/O data buffer.
MFC r257054:
Some microoptimizations for da and ada drivers:
 - Replace ordered_tag_count counter with single flag;
 - From da remove outstanding_cmds counter, duplicating pending_ccbs list;
 - From da_softc remove unused links field.
MFC r260407:
Allow delete_method sysctl to be set to "DISABLE".
[automated] Merge in upstream-github/stable/9