[jdk16] RFR: 8259560: Zero m68k: "static assertion failed: align" after JDK-8252049

[Aleksey Shipilev]

Debian folks report that Zero m68k (and seems only that arch) fails the static assert added by JDK-8252049. It affects at least JDK 16, but would affect more releases once JDK-8252049 is backported.

/<<PKGBUILDDIR>>/src/hotspot/share/oops/methodData.hpp: In constructor 'MethodData::CompilerCounters::CompilerCounters()':
/<<PKGBUILDDIR>>/src/hotspot/share/oops/methodData.hpp:1987:55: error: static assertion failed: align
 1987 | static_assert(sizeof(_trap_hist) % HeapWordSize == 0, "align");
      |

I tried to massage the code so that `oops/methodData.hpp` is not touched when Zero is built (since Zero does not use compilers and related infra), but there are enough transitive dependencies to `oops/methodData.hpp` to make it quite messy. So instead I would just special-case it in place.

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Commit messages:
 - 8259560: Zero m68k: "static assertion failed: align" after JDK-8252049

Changes: https://git.openjdk.java.net/jdk16/pull/102/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk16&pr=102&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259560
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk16/pull/102.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16 pull/102/head:pull/102

PR: https://git.openjdk.java.net/jdk16/pull/102