x86: remove hacks to include functions

None of this is currently necessary, the spurious interrupt
stubs and exception entry code is included in the binary just
fine. To make matters worse, some data referenced lives in the
.intList section which is completely stripped out of the binary.

If in the future we find certain essential functions are being
garbage collected when they should not be, the proper way to
mitigate this is with KEEP() directives in the linker script.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>