RFR: 8274501: c2i entry barriers read int as long on AArch64

[Erik Österlund]

There was a bug in the x86_64 implementation of the c2i entry barriers. We read the CLD::_keep_alive int as a 64 bit integer, while it is of course in fact a 32 bit integer. It was fixed in the patch that ported it to x86_32 (JDK-8235262). However, somewhere in-between I think the wrong code was used as a basis for the AArch64 implementation, which now seemingly has inherited that same bug.

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Commit messages:
 - 8274501: c2i entry barriers read int as long on AArch64

Changes: https://git.openjdk.java.net/jdk/pull/5754/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5754&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274501
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5754.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5754/head:pull/5754

PR: https://git.openjdk.java.net/jdk/pull/5754