RFR(XS): 8239363: PPC64: Wrong code generation after JDK-8183574

[Doerr, Martin]

Hi,

JDK-8183574: "Unify the is_power_of_2 functions" broke a piece of PPC64 code.

Issue with more details:
https://bugs.openjdk.java.net/browse/JDK-8239363

We need to restore usage of log2_long.
Webrev:
http://cr.openjdk.java.net/~mdoerr/8239363_ppc64_andi/webrev.00/

Please review.

Best regards,
Martin