powerpc: Add atomic_testand_{set,clear}_{int,long}

Add machine-optimized implementations for the following:

• atomic_testandset_int
• atomic_testandclear_int
• atomic_testandset_long
• atomic_testandclear_long

This fixes the build with ISA_206_ATOMICS enabled.
Add the associated atomic_testandset_32, atomic_testandclear_32, so
that ice(4) can potentially build.