FreeBSD: VOP_MMAP has been dead since 1996

Clang complains that our (K&R!) declaration of struct vop_mmap_args
will only be visible within the (empty) function.
With the kernel's CFLAGS, though, this is fatal.
Remove the dead code.

Reviewed-on: http://gerrit.openafs.org/9856
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit a63e6747abd33fef40da16312dfc22d052bffd00)

Change-Id: I538e8ba387a3fd90bcb89ea8faac7ad6973aa7f3
FBSD: Remove include directive for nonexistent file

In the bsd.kmod.mk world, this becomes a fatal error.

Reviewed-on: http://gerrit.openafs.org/5033
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 037f3251cd8fa318ad8320a061368efedc480c37)

Change-Id: Ief03a620ed4ce2cf84dd90a84df4a2ab1247fd9a
Catch up to FreeBSD VM object read/write locks

Upstream r248084 changed the vm_object mutex to be a rwlock,
allowing for future optimizations.  This is a KPI change, so
introduce conditionals to be compatible with both versions of the KPI.

Change-Id: I6e3101bc80262480035dee4c5b2d1b9cbc44b57b
Reviewed-on: http://gerrit.openafs.org/10295
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Fix build for FreeBSD 10.0

Move a rmlock.h inclusion up a bit so that the vm headers can get the
rmlock assertion (and other) macros they need.

The filedesc structure has been expanded on FreeBSD to support a
stronger capabilities system; getting to the actual file descriptor
requires another structure access.

limits.h and stdarg.h need sys/ and machine/ prefixes for inclusion in the
kernel on FreeBSD.  Unlike on master, we did not have extra -I arguments
to remove.

Catch up to VM layer changes.

This builds, but crashes at runtime due to some ABI incompatibilities
that appear in the rx event layer; those will be fixed in a separate patch.

Change-Id: Icc253b1e938a58a7ab8d1b789c82b9b940d263fd