syslinux: fix boot hang when host-gcc is 5.3

syslinux: fix boot hang when host-gcc is 5.3

Syslinux uses the host version of gcc to build to bootloader. On systems
with gcc 5.3, this results in a bootloader that hangs. This issue has
been addressed in upstream syslinux, but an official release has not
been made yet. This commit adds the upstream patch to fix the issue.

Most likely fixes bug #8866.

Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>