MFC r323206: Enable dtrace support for mips64 and the ERL kernel config

Turn on the required options in the ERL config file, and ensure
that the fbt module is listed as a dependency for mips in
the modules/dtrace/dtraceall/dtraceall.c file.

MFC r314651,r318439,r318440:

r314651:

sys/modules: normalize .CURDIR-relative paths to SRCTOP

This simplifies make output/logic

Tested with: `cd sys/modules; make ALL_MODULES=` on amd64

r318439:

Normalize .PATH on SRCTOP

This will help Jenkins dedupe 9 warnings between the static build and
the module build of ipsec(4).

Missed in SRCTOP conversion in r314651.

MFC with: r314651

r318440:

Normalize SYSDIR on SRCTOP instead of .CURDIR

This is being done to simplify pathing for CFLAGS and source files.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Use SYSDIR to reference to the top of the sys hierarchy. Define SYSDIR
relative to .CURDIR if not already defined. This makes the makefiles
more readable but also more re-usable and adaptable.

Obtained from: Juniper Networks, Inc.

opensolaris code: translate INVARIANTS to DEBUG and ZFS_DEBUG

Do this by forcing inclusion of
sys/cddl/compat/opensolaris/sys/debug_compat.h
via -include option into all source files from OpenSolaris.
Note that this -include option must always be after -include opt_global.h.

Additionally, remove forced definition of DEBUG for some modules and fix
their build without DEBUG.

Also, meaning of DEBUG was overloaded to enable WITNESS support for some
OpenSolaris (primarily ZFS) locks. Now this overloading is removed and
that use of DEBUG is replaced with a new option OPENSOLARIS_WITNESS.

MFC after: 17 days

The dtnfsclient module dependency should only be added if the old NFS
client support was compiled in.

Fix make buildworld -DMODULES_WITH_WORLD on i386

add DTrace systrace support for linux32 and freebsd32 on amd64 syscalls

Add systrace_linux32 and systrace_freebsd32 modules which provide
support for tracing compat system calls in addition to native system
call tracing provided by systrace module.

Provided that all the systrace modules are loaded now you can select
what syscalls to trace in the following manner:

syscall::xxx:yyy - work on all system calls that match the specification
syscall:freebsd:xxx:yyy - only native system calls
syscall:linux32:xxx:yyy - linux32 compat system calls
syscall:freebsd32:xxx:yyy - freebsd32 compat system calls on amd64

PR: kern/152822
Submitted by: Artem Belevich <fbsdlist@src.cx>
Reviewed by: jhb (earlier version)
MFC after: 3 weeks

Add the DTrace kernel module makefiles.