Revision 222557

MFC r219561, r220437:
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:linux:xxx:yyy - linux compat system calls (linux32 on amd64)
syscall:freebsd32:xxx:yyy - freebsd32 compat system calls on amd64

PR:         kern/152822
Reviewed by:        jhb (earlier version)
Approved by:	avg (mentor)