RFR: 8265484: Fix up TRAPS usage in GenerateOopMap::compute_map and callers

[David Holmes]

If compute_map encounters malformed bytecode, or an OOM condition then it can raise a LinkageError to be thrown in regular JavaThreads, and this is reflected in the use of TRAPS in a couple of methods. But for non-JavaThreads, and compiler threads, the occurrence of such an error is treated as a fatal error and we abort the VM.

In addition, most of the callers of compute_map actually use the CATCH macro, which just clears the exception and will abort a non-product VM.

This use of TRAPS is a problem for the change to convert TRAPS to JavaThread, because these methods are called by non-JavaThreads. To address this we change compute_map to create, but not throw, the exception and return a bool indicating whether an error occurred, and the caller can then choose to throw the exception itself. 

Testing: tiers 1-3

Thanks,
David

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Commit messages:
 - 8265484: Fix up TRAPS usage in GenerateOopMap::compute_map and callers

Changes: https://git.openjdk.java.net/jdk/pull/3580/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3580&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265484
  Stats: 44 lines in 4 files changed: 16 ins; 11 del; 17 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3580.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3580/head:pull/3580

PR: https://git.openjdk.java.net/jdk/pull/3580