Use threadalloc to create gc_worker threads (and eventually use it
for lwIP threads.)

make crange compile

Not important yet; in fact, none of the benchmarks run long enough to do gc

All our machines, however, have e1000e cards.

..basic e1000 initialization fails on ud0 due to reading EEPROM via
EERD.

Conflicts:
	main.c

rcu -> gc

..There is not yet code to read the e820 map from the BIOS.

This requires switching from -mcmodel=kernel to -mcmodel=large.  The
performance hit appears to be small.

Instead of using ld -b binary, build incbin.S, which uses gas' .incbin.

e.g. "make" and "make HW=qemu" build for qemu
     "make HW=josmp" builds for josmp