Bug-456171 [PATCH] FreeBSD: Don't record address errors when accessing the 'kern...

Bug-456171 [PATCH] FreeBSD: Don't record address errors when accessing the 'kern.ps_strings' sysctl struct

There is quite a lot of stuff here.

The problem is that setproctitle and kern.ps_strings were using the Valgrind host auxv
rather than the guest. The proposed patch would have just ignored those memory ranges.

I've gone a fair bit further than that
1. refactored the initimg code for building the client auxv. Previously we were
   simply ignoring any non-scalar entries. Now we copy most of thse as well.
   That means that 'strtab' built on the client stack no longet only contains
   strings, at can also now contain binary structures. Note I was a bit
   concerned that there may be some alignment issues, but I haven't seen any
   problems so far.
2. Added intercepts to sysctl and sysctlbyname for kern.ps_strings, then find
   AT_PS_STRINGS from the client auxv that is now usable from step 1.
3. Some refactoring of sysctl and sysctlbyname syscall wrappers. More to do
   there!
4. Added a setproctitle testcase (that also tests the sysctls).
5. Updated the auxv testcase now that more AT_* entries are handled.