switch to ELF naming for local labels.

Add END(func)
Fix some straggling %r@<eol> to (%r)

Convert to normal Motorola syntax for addressing.
%r@ -> (%r)
%r@- -> -(%r)
%r@+ -> (%r)+
%r@(n) n(%r)
etc.
No object differences.

Merge libkern + libc common files. As requested by core.