ao-load: Make ao_sym static to avoid collision with ao-editaltos

ao-load: Make ao_sym static to avoid collision with ao-editaltos

ao-load doesn't use ao-editaltos at this point, but does share the
same name for the symbol table. To make the linker happier, make the
ao-load version static.

Signed-off-by: Keith Packard <keithp@keithp.com>