patches/gdb: Fix canadian building of GDB for powerpc

Adds patch for GDB v6.8, v7.0, v7.0.1 to fix canadian
cross building of GDB for powerpc.

See original patch information here:
http://sources.redhat.com/bugzilla/show_bug.cgi?id=9638

The patch is not required for GDB v7.1 (fixed).

Tested in canadian combination using mingw32 and powerpc toolchains.
Tested to not affect normal cross building of GDB for powerpc target.

Signed-off-by: Martin Lund <mgl@doredevelopment.dk>

# Blackfin specific configuration file

config ARCH_blackfin

    select ARCH_SUPPORTS_32

    select ARCH_DEFAULT_32

    select ARCH_DEFAULT_LE

    select ARCH_SUPPORT_ARCH

    select ARCH_SUPPORT_CPU

    select ARCH_SUPPORT_TUNE

    select ARCH_SUPPORT_FPU

     help

      The Blackfin architecture