RFR: 8302155: [AIX] NUM_LCPU is not required variable

[Amit Kumar]

We don't need NUM_LCPU, it's just a small code change which removes this variable. I've tested it on AIX and cores are detected successfully with changes. 
@backwaterred please take look at it. 
 Suggestions are welcomed :)

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Commit messages:
 - could be removed

Changes: https://git.openjdk.org/jdk/pull/12494/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12494&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302155
  Stats: 4 lines in 1 file changed: 0 ins; 3 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12494.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12494/head:pull/12494

PR: https://git.openjdk.org/jdk/pull/12494