Prepare for uploading 7.0.27+dfsg-4 (in sid branch of our boinc repository)

[Guo Yixuan]

Hello,

As boinc 7.0.28 in master have some problem with SETI (segfaults, while
7.0.27 is fine), and it's near freeze, I think it's proper to
backport(cherry-pick) some changes in master onto 7.0.27, so I created
the sid branch (with version 7.0.27+dfsg-4), and hoping to upload it in
to sid, and then re-enter testing.

I've cherry-picked these commits from master to sid branch:

0845a6e -> f41f790 Adding hardening compiler flags
0f65a16 -> cf0e8ac Fixed typos.
456dfda -> 464c85d Closing #672725
7bde97b -> d6c5b76 Add patch from Rom that fix project category crash
2dcb33c -> 0258d59 Make sched/transitioner_catchup.php executable.
d6b251e -> 283b7e9 Upon request: increasing priority of boinc client

Major changes since 7.0.27+dfsg-3

  1. Don't build boinc-amd-opencl package, (depends on fglrx-driver
which is removed from testing, and so boinc was removed, too). This is a
temporary solution, after fglrx-driver get into testing, we can readd it.
  2. Hardening flags
  3. Hurd FTBFS (#672725)
  4. Project category crash patch. (#641593)
  5. Increase priority of boinc client

Not cherry-picked:

  1. Commits related to boinc-screensaver, because it's not ready in master.
  2. boinc-dev -> libboinc* split, this is a big change, so I'd rather
see boinc in testing before addressing this.

As most of the cherry-picked commits' author is Steffen, I think it's
proper to add changelog entry for him like this:

  [ Steffen Moeller ]
  * Not building boinc-amd-opencl, for fglrx-driver is not in testing.
  * Adding hardening flags.
  * Addressed FTBFS on hurd (Closes: #672725)

  [ Guo Yixuan ]
  * Add patch from Rom that fix the project category crash. (Closes:
#641593)
  * Cherry-picking above commits from master to sid branch.

Please comment on this proposal, or raise objections, if any.

Cheers,

Guo Yixuan