[Rev 03] RFR: Add a limition to allocate object heap in aarch64 with tsan enabled.

[Jie He]

> Vm will calculate max heap size according to the physical ram if user
> doesn't specify the size(-Xmx). However, with tsan 48-bits memory
> mapping of aarch64, it's hard to allocate the large continuous vm
> space. Heap allocation often fail in this case, thus, add a limitation
> at the end of the heap size calculation to prevent to exceed the
> avaiable size. Currently, only support 48-bits address space.
> 
> Can reproduce the behavior by launching "java --version" in a machine
> with huge physical memory.

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  Add a limit to allocate object heap in aarch64 with tsan enabled.
  
  Vm will calculate max heap size according to the physical ram if user
  doesn't specify the size(-Xmx). However, with tsan 48-bits memory
  mapping of aarch64, it's hard to allocate the large continuous vm
  space. Heap allocation often fail in this case, thus, add a limit
  at os::has_allocatable_memory_limit to prevent to exceed the
  avaiable size. Currently, only support 48-bits address space.
  
  Can reproduce the behavior by launching "java --version" in a machine
  with huge physical memory.
  
  Change-Id: Iabff934444091436bc657978e2e947c270398f29

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

Changes:
  - all: https://git.openjdk.java.net/tsan/pull/6/files
  - new: https://git.openjdk.java.net/tsan/pull/6/files/a88d78bb..0ff7ead6

Webrevs:
 - full: https://webrevs.openjdk.java.net/tsan/6/webrev.03
 - incr: https://webrevs.openjdk.java.net/tsan/6/webrev.02-03

  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/tsan/pull/6.diff
  Fetch: git fetch https://git.openjdk.java.net/tsan pull/6/head:pull/6

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