DTrace port

[Darran Hunt <darran%NetBSD.org@localhost>]

Courtesy of CoyotePoint Systems, I've been working on a port of DTrace  
(http://en.wikipedia.org/wiki/DTrace) to NetBSD for i386.  The port is  
based on the FreeBSD-8 port and is close to the point where it would  
be useful to import it to current and make it available for any  
interested parties to experiment with it and, for example, add  
providers.

The port adds libdwarf, libctf, ctfconvert, and ctfmerge tools to the  
toolchain, and CTF generation to the make framework.  I've made  
everything optional based on a MKDTRACE build knob which will be off  
by default.

DTrace is CDDL licensed (like ZFS) and will live in the external/cddl/ 
osnet directory.

At the moment the kernel module builds and loads, and its able to  
execute a basic hello world D script using the built-in BEGIN/END  
provider.  It is still needs work to support kernel modules, user- 
space tracing (via libproc), providers (fbt, sdt, systrace, profiler,  
lockstat, etc), and a few other bit and pieces marked with "XXX TBD"  
comments in the code.  It doesn't do much at the moment but once  
providers are completed DTrace will enable interesting views into the  
kernel for inspection and profiling, and debugging.

Regards,
Darran.