RFR: 8287362: FieldAccessWatch testcase failed on AIX platform

[Ichiroh Takiguchi]

On AIX platform, `test/hotspot/jtreg/serviceability/jvmti/FieldAccessWatch/FieldAccessWatch.java` testcase failed by single testcase execution.

Failure message is:

Error occurred during initialization of VM
agent library failed to init: FieldAccessWatch
Failed to set capabilities, error: 98

It seems following initialization code affects this issue

jvmtiCapabilities caps = {0};

So additionally `memset()` is required just for AIX platform

-------------

Commit messages:
 - 8287362: FieldAccessWatch testcase failed on AIX platform

Changes: https://git.openjdk.java.net/jdk/pull/8904/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8904&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287362
  Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8904.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8904/head:pull/8904

PR: https://git.openjdk.java.net/jdk/pull/8904