RFR: JDK-8276175: codestrings.validate_vm gtest still broken on ppc64 after JDK-8276046

[Thomas Stuefe]

Frustratingly, JDK-8276046 failed to work because the #ifdef PPC was added to the existing group of #ifdefs at the very start of test_codestrings.cpp.

PPC is not a primary macro however, it gets set via macros.hpp if one of PPC32 or PPC64 is set. Therefore this only works after the inclusion of macro.hpp (Works for ZERO and PRODUCT, since those are primary macros).

This fix revives my original fix using the DISABLED_... moniker on test functions. That seems to be the default way to disable tests anyway.

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Commit messages:
 - Use DISABLED_ prefix to switch off test on ppc

Changes: https://git.openjdk.java.net/jdk/pull/6174/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6174&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8276175
  Stats: 8 lines in 1 file changed: 5 ins; 3 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6174.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6174/head:pull/6174

PR: https://git.openjdk.java.net/jdk/pull/6174