Some fixes for aelflod and aslod.

Copy rhead() and rsect() from aslod to aelflod, so aelflod can work
for machine with 64-bit long.

In aelflod, fix ELF header so file(1) no longer reports "corrupted
section header size".

Signed-off-by: Manoel Trapier <godzil@godzil.net>