GCC 4.7 runtime library plans

[Michael Hope]

Hi Ricardo, Matthias.  GCC 4.7 is almost here and it's likely that
Linaro GCC 4.7 will come out for next month's 2012.04 milestone.

For the binary toolchain to work we need the 4.7 runtime libraries on
the target.  Matthias, what are your plans?  How much of 4.7 is
packaged so far?  Ricardo, could we pull these updates to libgcc,
libstdc++, and others into the LEB?

These should be backwards compatible but there's always a risk.  Using
the 4.5 runtime with a 4.4 compiler back on Maverick was OK.

-- Michaele