RFR: 8205187: javac/javadoc should not crash if no java.lang; crash message obsolete

[Vicente Romero]

Please review this PR which is basically changing the error message the compiler shows if the package java.lang can't be found, the current message is obsolete,

TIA

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Commit messages:
 - 8205187: javac/javadoc should not crash if no java.lang; crash message obsolete

Changes: https://git.openjdk.java.net/jdk/pull/6898/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6898&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8205187
  Stats: 23 lines in 4 files changed: 8 ins; 6 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6898.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6898/head:pull/6898

PR: https://git.openjdk.java.net/jdk/pull/6898