tinymembench: add patch to fix build on Cortex-M

This commit adds a patch to the tinymembench package that fixes the
build on Thumb-only architectures such as ARM Cortex-M. The patch has
been submitted upstream in
https://github.com/ssvb/tinymembench/pull/13.

Fixes:

  http://autobuild.buildroot.net/results/5f0148cef22b3b9aee691e1702722a0bbc68c8e8/



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