* remove now-unused D_SBIG (was for typestrings)
 * rename elf64.[ch] to elf.[ch]
 * pull in elf headers from FreeBSD instead of writing our own
 * emit non-header ELF data in data section
 * stub out a few more ELF sections needed for dynamic loading

R=r
DELTA=1928  (1237 added, 635 deleted, 56 changed)
OCL=33642
CL=33658