package/binutils: fix loops relaxation in xtensa gas

package/binutils: fix loops relaxation in xtensa gas

Loop relaxation logic in xtensa gas may produce code in which LEND
register doesn't match actual zero overhead loop end. Fix relaxation
code so that it produces a literal or a pair of const16 instructions
with associated relocation record that works correctly in the presence
of other relaxations. This fixes crash in X11 server caused by window
movement.

Loop relaxation has limited of 32K range, this fix removes this
limitation.

Fixes:
http://autobuild.buildroot.net/results/e05522ce540f4ac23f9a3a8fec724694d9a23101/

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>