Compile fixes:

Remove duplicate "debug_ktr.mask" sysctl definition.
Remove now unused variable from "kern_ktr.c".
This fixes build of "ktr" which was broken by r267961.

Let the default value for "vm_kmem_size_scale" be zero. It is setup
after that the sysctl has been initialized from "getenv()" in the
"kmeminit()" function to equal the "VM_KMEM_SIZE_MAX" value, if
zero. On Sparc64 the "VM_KMEM_SIZE_MAX" macro is not a constant. This
fixes build of Sparc64 which was broken by r267961.

Add a special macro to dynamically create SYSCTL root nodes, because
root nodes have a special parent. This fixes build of existing OFED
module and CANBUS module for pc98 which was broken by r267961.

Add missing "sysctl.h" includes to get the needed sysctl header file
declarations. This is needed after r267961.

MFC after:	2 weeks
Move the -I of common/util to the proper place to fix the powerpc build.

MFC after:	2 weeks
Revert	r267869:

MFV	r260708
4427 pid provider rejects probes with valid UTF-8 names

Use of u8_textprep.c broke the build on powerpc.

Reported by:	bz, rpaulo and tinderbox.
Pointyhat:	me
There might be a potential race condition for the NFSv4 client
when a newly created file has another open done on it that
update the open mode. This patch moves the code that updates
the open mode up into the block where the mutex is held to
ensure this cannot happen. No bug caused by this potential
race has been observed, but this fix is a safety belt to ensure
it cannot happen.

MFC after:	2 weeks
Give each interrupt a descriptive name when using MSIX

MFC after:	3 days
Reduce some warnings in the Solaris unicode support.

Clean some warnings from parenthesis and minor style issues.

MFC after:	3 days
Merge branch 'master' of https://github.com/freebsd/freebsd