Archive rebuild with GCC 6

[Lucas Nussbaum <lucas@debian.org>]

Hi,

I just did an archive rebuild with the gcc-defaults package from
experimental, to use GCC 6.

I filed quite a lot of bugs.

All logs (of failed builds) are available at
https://people.debian.org/~lucas/logs/2016/07/13/

Due to the large number of problems, there could be a couple of cases
where I filed bugs on a per-package basis, rather than on the package
causing all the failures.

This is most likely the case for:
- a set of failures related to math functions/macros. grepping for min,
  max, isnan in results:  http://blop.info/pub/math_functions.txt

- a set of failures related to the inclusion of stdlib.h (?):
  http://blop.info/pub/stdlib_h.txt

Also, there's a large number of packages with a linking problem related
to boost's regex support. The full list of affected packages is at
http://blop.info/pub/boost_regex.txt
I wasn't sure of what's happening here, and did _not_ file bugs for
those.

Lucas