FYI: update for Python 2.7

[Michael Snyder]

Tom Tromey wrote:
> I am checking this in.
> 
> Python 2.7 was recently released.  This patch updates GDB to build
> correctly against it.
> 
> I built this on my x86 box, with a local Python 2.7 build.
> I ran the gdb.python tests with the new gdb without errors.
> 
> Tom

Do we need a separate change for --with-python=?

checking whether to use python... /build/toolchain/lin32/python-2.6/
configure: error: invalid value for --with-python
make[1]: *** [configure-gdb] Error 1