distribution/build: making debugging easier

[Werner Almesberger]

During last night's debugging chase, I noticed two small things
our distribution/build could improve to make debugging easier:

1) Make vmlinux of the kernel build available. Doesn't have to be
   at the same place as the uImage but should be easy to find from
   there, e.g., in a subdirectory.

   Without it, it's very difficult to use exactly the same kernel
   as a bug reporter and at the same time have access to the
   debugging symbols.

2) Our strace isn't quite in sync with the kernel. Three examples
   from #2071:

   317   SYS_294(0x3, 0x1, 0x2, 0xbec5dc4c, 0x4) = 0
   317   SYS_283(0x3, 0xbec5dbde, 0x1d, 0, 0xbec5dbe0) = -1 ENOENT (No such file or directory)
   ...
   317   mq_notify(1, {...})               = 3

   The first two are sys_setsockopt and sys_connect. Not sure what the
   third is, but mq_notify seems unlikely.

Note sure if strace's system call mismatch is an OE or an OM problem.

Thanks,
- Werner