gdb: add support for gdb 7.10

gdb: add support for gdb 7.10

This commit adds support for gdb 7.10.

gdb 7.9.1 carries the following patches:

 - 0001-gdbserver-fix-uClibc-whithout-MMU.patch
   merged as 6282837972a5c7b89968319caf821fcbd2a166bb, and part of 7.10

 - 0002-gdbserver-xtensa-drop-xtensa_usrregs_info.patch
   merged as deb44829ecc1dd38275af0fcf91acd319e227a89, and part of 7.10

 - 0003-gdbserver-xtensa-fix-typo-in-XCHAL_HAVE_LOOPS.patch
   merged as a2d5a9d76f2366ed93095fc5a63eafa06b22f808, and part of 7.10

Consequently, none of the three patches we have for 7.9.1 are useful
for 7.10.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>