FreeBSD_HEAD_amd64_gcc4.9 - Build #263 - Fixed

FreeBSD_HEAD_amd64_gcc4.9 - Build #263 - Fixed:

Build information: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/263/
Full change log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/263/changes
Full build log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/263/console

Change summaries:

286118 by hselasky:
Limit the number of times we loop inside the DWC OTG poll handler to
avoid starving other fast interrupts. Fix a comment while at it.

MFC after:	1 week
Suggested by:	Svatopluk Kraus <onwahe_at_gmail.com>

286114 by ae:
Ansify if_stf.c

286112 by ae:
Remove unneded #include "opt_inet.h".

286111 by ed:
Document the existence of cloudabi_load and cloudabi64_load.

286110 by jmg:
temporarily fix build..  This isn't the final fix, and testing is
still on going, but it has passed world for mips and powerpc...

I know this has an extra semicolon, but this is the patch that is
tested...

Looks like better fix is to use _Static_assert...

286107 by np:
cxgbe(4): initialize debug_flags from the kernel environment.

MFC after:	3 days

286106 by kib:
vn_io_fault() handling of the LOR for i/o into the file-backed buffers
has observable overhead when the buffer pages are not resident or not
mapped.  The overhead comes at least from two factors, one is the
additional work needed to detect the situation, prepare and execute
the rollbacks.  Another is the consequence of the i/o splitting into
the batches of the held pages, causing filesystems see series of the
smaller i/o requests instead of the single large request.

Note that expected case of the resident i/o buffer does not expose
these issues.  Provide a prefaulting for the userspace i/o buffers,
disabled by default.  I am careful of not enabling prefaulting by
default for now, since it would be detrimental for the applications
which speculatively pass extra-large buffers of anonymous memory to
not deal with buffer sizing (if such apps exist).

Found and tested by:	bde, emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

286103 by jmg:
The implementation note isn't true anymore..

Not that anyone reads it, but those that do, remind them that this
isn't usable in userland...  I can't wait till this doc is wrong..