RFR: 8272558: IR Test Framework README misses some flags

[Tobias Hartmann]

The README misses `-DExcludeRandom`, `-DReportStdout` and `-DPreferCommandLineFlags`. I also changed `-DIgnoreCompilerControls=false` to `-DIgnoreCompilerControls=true` because `false` is the default and added a missing `D` to `-DTestCompilationTimeout`.

Thanks,
Tobias

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Commit messages:
 - Adjusted description, removed whitespace at end of lines
 - 8272558: IR Test Framework README misses some flags

Changes: https://git.openjdk.java.net/jdk/pull/5138/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5138&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272558
  Stats: 17 lines in 1 file changed: 2 ins; 0 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5138.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5138/head:pull/5138

PR: https://git.openjdk.java.net/jdk/pull/5138