An attempt to build ICU on old macOS with PowerPC leads to an issue:
```
./out/tmp/icudt72b_dat.S:7:Unknown pseudo-op: .balign
./out/tmp/icudt72b_dat.S:7:Rest of line ignored. 1st junk character valued 49 (1).
```
Why? Because `as` is too old.
Anyway, switch back to `.p2align` fix a build and allows to pass all tests.
See: https://trac.macports.org/ticket/66258
Signed-off-by: Kirill A. Korinsky <kirill@korins.ky>
