RFR: Add a limition to allocate object heap in aarch64 with tsan enabled.

[Man Cao]

On Tue, 21 Apr 2020 09:39:56 GMT, Jie He <github.com+10233373+jhe33 at openjdk.org> wrote:

>> I will move it and test x86. thank you for reminding.
>
> @caoman I think it's better to put the code into os_posix.cpp with TSAN_ONLY, AARCH64_ONLY, not os_linux_aarch64.cpp,
> because latter has to make multiple copies of function has_allocatable_memory_limit for archtectures. And in
> os_linux.cpp, AARCH64, X86_64 specific code is allowed. what do you think?

Putting the code related to reasonable_max in os_posix.cpp sounds good.
It's better to guard it with TSAN_RUNTIME_ONLY(). We would like to keep "-XX:-ThreadSanitizer" the same as the default
JVM configuration.

-------------

PR: https://git.openjdk.java.net/tsan/pull/6