Move the TacOS VM under the src/test directory.

Use sed to replace the path to the TacOS ISO in the vmx file.
Add the .note.GNU-stack section to src/arch/i386/boot/tss.S.

This makes the whole kernel have a non-executable stack.
Fix linking with ld 2.19.

Discard all unneeded sections.  The .note.gnu.build-id section showed up, which
ld tried to link before the .text section.  This caused grub to flip out and
claim that the kernel didn't fit in memory.
Enable garbage collection of unused sections.