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>

 # MIPS specific config options

 config ARCH_mips

     select ARCH_SUPPORTS_32

     select ARCH_SUPPORTS_64 if EXPERIMENTAL

     select ARCH_DEFAULT_32

     select ARCH_USE_MMU

     select ARCH_SUPPORTS_BOTH_ENDIAN

     select ARCH_DEFAULT_BE

     select ARCH_SUPPORT_ARCH

     select ARCH_SUPPORT_ABI

     select ARCH_SUPPORT_TUNE

     help

       The MIPS architecture, as defined by:

         http://www.mips.com/