For POWER4..POWER8 we align loops of 5..8 instructions to 32 bytes
(instead of to 16 bytes) because that executes faster. This is no
longer the case on POWER9, so we can just as well only align to 16
bytes.
* config/rs6000/rs6000.c (rs6000_loop_align): Don't align tiny loops
to 32 bytes when compiling for POWER9.
From-SVN: r258260
