btrfsprogs: upgrade to current git master
linux-3.10: backport a fix for "btrfs send"

It has been submitted for inclusion in mainline, so it will probably
make it into 3.11 (or 3.12 as 3.11 is fairly close to release).

It is very local, only affecting people who use the "send" feature.
Without it, send is unstable/unsafe to use incrementally.

It can probably be applied to 3.9 and 3.8 as well, but as I only
tested it against 3.10, so I didn't bother.
Revert "Add taskjuggler ruby gem"

This reverts commit 67a46ce928c9190c9b11982120000df711ef1945.

It seems this commit is the reason for this hydra breakage:

  [pbuilding /nix/store/hwdyx4mf5638mxkka64cxjcj75vw3hmz-nixpkgs-tarball-1.0pre28245_67a46ce
  [punpacking sources
  [...snip lots of stuff...]
  'manual.pdf' successfully built
  [qmake: Leaving directory `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/doc'
  [q[q[prunning tests
  [pchecking pkgs/top-level/all-packages.nix on i686-linux
  error: while evaluating the attribute `drvPath' at `/nix/store/l7ny7f17aii5qfgmadr2wcp3wan54wlp-nix-1.5.3/share/nix/corepkgs/derivation.nix:19:9':
  while evaluating the builtin function `derivationStrict':
  while instantiating the derivation named `ruby-actionmailer-4.0.0' at `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/pkgs/development/interpreters/ruby/gem.nix:16:5':
  while evaluating the derivation attribute `propagatedNativeBuildInputs' at `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/pkgs/stdenv/generic/default.nix:78:17':
  while evaluating the attribute `outPath' at `/nix/store/l7ny7f17aii5qfgmadr2wcp3wan54wlp-nix-1.5.3/share/nix/corepkgs/derivation.nix:18:9':
  while evaluating the builtin function `getAttr':
  while evaluating the builtin function `derivationStrict':
  while instantiating the derivation named `ruby-actionpack-4.0.0' at `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/pkgs/development/interpreters/ruby/gem.nix:16:5':
  while evaluating the derivation attribute `propagatedNativeBuildInputs' at `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/pkgs/stdenv/generic/default.nix:78:17':
  while evaluating the attribute `outPath' at `/nix/store/l7ny7f17aii5qfgmadr2wcp3wan54wlp-nix-1.5.3/share/nix/corepkgs/derivation.nix:18:9':
  while evaluating the builtin function `getAttr':
  while evaluating the builtin function `derivationStrict':
  while instantiating the derivation named `ruby-activesupport-4.0.0' at `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/pkgs/development/interpreters/ruby/gem.nix:16:5':
  while evaluating the derivation attribute `propagatedNativeBuildInputs' at `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/pkgs/stdenv/generic/default.nix:78:17':
  while evaluating the attribute `outPath' at `/nix/store/l7ny7f17aii5qfgmadr2wcp3wan54wlp-nix-1.5.3/share/nix/corepkgs/derivation.nix:18:9':
  while evaluating the builtin function `getAttr':
  while evaluating the builtin function `derivationStrict':
  while instantiating the derivation named `ruby-multi_json-1.7.8' at `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/pkgs/development/interpreters/ruby/gem.nix:16:5':
  while evaluating the derivation attribute `src' at `/tmp/nix-build-nixpkgs-tarball-1.0pre28245_67a46ce.drv-0/git-export/pkgs/development/interpreters/ruby/gem.nix:11:5':
  while evaluating the attribute `outPath' at `/nix/store/l7ny7f17aii5qfgmadr2wcp3wan54wlp-nix-1.5.3/share/nix/corepkgs/derivation.nix:18:9':
  while evaluating the builtin function `getAttr':
  while evaluating the builtin function `derivationStrict':
  hash `no hash' has wrong length for hash type `sha256'
  [q[q[qbuild time elapsed:  0m0.038s 0m0.023s 0m20.586s 0m2.004s
  builder for `/nix/store/lxmyqg7z1l71ji5vdar2m5w66dx45v20-nixpkgs-tarball-1.0pre28245_67a46ce.drv' failed with exit code 1
  error: build of `/nix/store/lxmyqg7z1l71ji5vdar2m5w66dx45v20-nixpkgs-tarball-1.0pre28245_67a46ce.drv' failed
virtualbox: fix extension pack hash (must be base16)
liburcu: new package

liburcu is a userspace RCU (read-copy-update) library that is used by
LTTng - Linux Trace Toolkit (next generation).
lttng-ust: new package

This is the user space library for LTTng. It is needed to do user space
tracing, as opposed to kernel space tracing.
lttng-tools: new package

This is the Linux Trace Toolkit. Included in this package:

Command-line client:
  lttng
Tracing daemons:
  lttng-sessiond (automatically started by lttng)
  lttng-relayd   (remote trace collection daemon)

Userspace tracing can be done by using liblttng-ust. To do kernel
tracing we also need the LTTng kernel modules.

I've added a patch that changes "/sbin/modprobe" to just "modprobe".
babeltrace: new package

Babeltrace is a command-line tool and library to read and convert LTTng
tracefiles. Give it a (binary) trace file/dir path and it will print a
human readable event log to standard out.
lttv: new package

Linux Trace Toolkit Viewer is a GUI program to visualize LTTng trace
files. (An alternative to this program is the LTTng plugin for the
Eclipse IDE.)
lttng-modules: new package

Add linux kernel modules needed to do kernel tracing with LTTng.

To make them available in NixOS (needed by lttng-sessiond to load lttng
modules), add this to configuration.nix:

  boot.extraModulePackages = [ pkgs.linuxPackages.lttngModules ];