RFR: JDK-8304867: Explicitly disable dtrace for ppc builds

[Matthias Baesken]

Currently the support for the JVM feature 'dtrace' is not implemented in the HS codebase on ppc, so we should disable it in the jvm-features make detection as well. Otherwise we could run into building with dtrace feature support if e.g. the 'dtrace' tool and related header(s) are available on the build machine.

Probably the same is true for the s390x platform, see
https://github.com/openjdk/jdk/blob/0deb648985b018653ccdaf193dc13b3cf21c088a/src/hotspot/cpu/s390/c1_LIRAssembler_s390.cpp#L226
but I only looked a bit more into ppc.

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Commit messages:
 - JDK-8304867

Changes: https://git.openjdk.org/jdk/pull/13173/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13173&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304867
  Stats: 5 lines in 1 file changed: 3 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13173.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13173/head:pull/13173

PR: https://git.openjdk.org/jdk/pull/13173