boot/syslinux: fix build with binutils note gnu property section

boot/syslinux: fix build with binutils note gnu property section

Fixes #11756

This fixes the following build error with newer binutils:

  objcopy -O binary mbr.elf mbr.bin
  perl /build/syslinux/src/syslinux/mbr/checksize.pl mbr.bin
  mbr.bin: too big (452 > 440)

Corresponding bug reports:

 - https://bugs.archlinux.org/task/60405
 - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=906414

Strip the .note.gnu.property in the linker scripts for the MBRs.

Signed-off-by: Christian Stewart <christian@paral.in>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>