binutils: don't default to 2.22

Lots of packages are failing with binutils 2.22 with undefined symbols,
as it defaults to --no-copy-dt-needed-entries. Long term, the packages
should get fixed, but let's keep it at 2.21.1 for now.

For more details, see:
- http://wiki.debian.org/ToolChain/DSOLinking
- https://wiki.ubuntu.com/NattyNarwhal/ToolchainTransition



Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>