RFR: 8280761: UseCompressedOops should be set after limit_heap_by_allocatable_memory

[KIRIYAMA Takuya]

I fixed to set UseCompressedOops flag after limit_heap_by_allocatable_memory(). 
So when ulimit -v is called and -XX:MaxRAM is set, UseCompressedOops does not become false. 
And all hotspot tier1 test are passed.
Would you please review this fix?

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Commit messages:
 - 8280761: UseCompressedOops should be set after limit_heap_by_allocatable_mem
 - 8280761: UseCompressedOops should be set after limit_heap_by_allocatable_memor

Changes: https://git.openjdk.java.net/jdk/pull/7938/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7938&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280761
  Stats: 127 lines in 2 files changed: 111 ins; 16 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7938.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7938/head:pull/7938

PR: https://git.openjdk.java.net/jdk/pull/7938