RFR: 8254586: Replace fthrow() calls with simpler method calls in classFileParser.cpp

[Harold Seigel]

Hi,
Please review this small change to simplify exception throwing in classFileParser.cpp  The change was tested with tiers
one and two on Windows, Linux x64, and Mac OSX, and with tiers 3-5 on Linux x64.

Thanks, Harold

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Commit messages:
 - 8254586: Replace fthrow() calls with simpler method calls in classFileParser.cpp

Changes: https://git.openjdk.java.net/jdk/pull/618/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=618&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254586
  Stats: 84 lines in 3 files changed: 37 ins; 31 del; 16 mod
  Patch: https://git.openjdk.java.net/jdk/pull/618.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/618/head:pull/618

PR: https://git.openjdk.java.net/jdk/pull/618