RFR: Enable aarch64 build in jdk/tsan.

[Jie He]

Enable INCLUDE_TSAN in aarch64, and add the option -fno-experiment-isel when build aarch64 to
avoid a known bug [1] in llvm-8, recommended compiler in jdk/tsan,
which generates wrong debug info.

In addition, change aarch64 release build option from -O3 to -Os to prevent a crash occurs
in build process, caused by a known issue [2].

[1] https://bugs.llvm.org/show_bug.cgi?id=40887
[2] https://bugs.llvm.org/show_bug.cgi?id=44581

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Commit messages:
 - Enable aarch64 build in jdk/tsan.

Changes: https://git.openjdk.java.net/tsan/pull/5/files
 Webrev: https://webrevs.openjdk.java.net/tsan/5/webrev.00
  Stats: 10 lines in 2 files changed: 8 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/tsan/pull/5.diff
  Fetch: git fetch https://git.openjdk.java.net/tsan pull/5/head:pull/5

PR: https://git.openjdk.java.net/tsan/pull/5