Nix trailing whitespace in files of membars, atomics, and lock stubs.

Will be touching many of these files soon for functional changes.

No functional change intended.

fix comment

Improve the code in __sync_bool_compare_and_swap_{1,2,4}.
- bccs is smaller and faster than bcc(.w) in this case.
- it can be used movql in this case (assembler optimise it though).

atomic_cas_{8,16}:
- Correct the wrong offset in stack.
__sync_bool_compare_and_swap_{1,2,4}:
- Correct the wrong offset in stack.
- D3 must be preserved in subroutines.
PR/49995.

Try to hide the C runtime implementation specific __sync_* ops from librump,
to avoid duplicates.

Simplify the variants returning a bool

Add a few __sync_* and atomic functions.

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.

enable profiling of assembly functions.

Remove clause 3 and 4 from TNF licenses

Add atomic_cas_foo_ni().

Pull in m68k atomic ops from the thorpej-atomic branch.