RFR: 8283799: Collapse identical catch branches in jdk.hotspot.agent

[Andrey Turbanov]

Let's take advantage of Java 7 languate feature - "Catching Multiple Exception Types".
It simplifies code. Reduce duplication.
Found by IntelliJ IDEA inspection `Identical 'catch' branches in 'try' statement`

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Commit messages:
 - [PATCH] Collapse identical catch branches in jdk.hotspot.agent

Changes: https://git.openjdk.java.net/jdk/pull/7973/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7973&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283799
  Stats: 47 lines in 8 files changed: 0 ins; 32 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7973.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7973/head:pull/7973

PR: https://git.openjdk.java.net/jdk/pull/7973