RFR: JDK-8281217: Source file launch with security manager enabled fails

[Jonathan Gibbons]

Please review a small change to the source-code launcher to formally reject the use of a security manager in programs launched by the source-code launcher.  This changes the previous behavior where it was tacitly allowed but would trigger an `IllegalAccessException` unless extra (effectively, all) privileges were granted to the `jdk.compiler` module.

The test is modified too reflect the new behavior.

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Commit messages:
 - JDK-8281217: Source file launch with security manager enabled fails

Changes: https://git.openjdk.java.net/jdk/pull/7518/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7518&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281217
  Stats: 67 lines in 3 files changed: 26 ins; 28 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7518.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7518/head:pull/7518

PR: https://git.openjdk.java.net/jdk/pull/7518