Heads up: x86 boot components link changes

Hi,

In base r358643 I committed a few changes in stand/i386, which cause
most of the x86 boot components (e.g /boot/boot, /boot/loader and so on)
to link using a linker script.  This is in preparation of the clang and
lld 10.0.0 import.

Even though I tested that the resulting binaries appear to work fine in
various scenarios, and look sane, there is always a possibility that it
will cause trouble in some situations.

Therefore, please take care when updating to r358643 and after, and if
you encounter problems that are certainly caused by it, let me know!

-Dimitry