syslinux.bbclass, syslinux: Update to syslinux 6.01
A newer version of syslinux is required for an EFI enabled isohybrid.
This is used for the the capability to generate 3 types of ISO images,
all of which can be booted off a USB device or HDD if copied with dd.
1) PC BIOS only ISO
2) EFI only ISO
3) EFI + PC BIOS ISO
The syslinux.bbclass required a minor tweak because a few .c32
libraries require dynamic loading from the created media as of
syslinux 5 and up. This was a good time to also fix the
duplication of the AUTO_SYSLINUXMENU block.
[YOCTO #4100]
Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Saul Wold <sgw@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
