RFR: 8275021: Test serviceability/sa/TestJmapCore.java fails with: java.io.IOException: Stack frame 0x4 not found [v2]

[Lin Zang]

> The root cause for the fail is that there must be a flush for `BufferedOutputStream` before getting the `pos` of the file, otherwise the data length is wrongly calculated.

Lin Zang has updated the pull request incrementally with one additional commit since the last revision:

  refine comments

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5890/files
  - new: https://git.openjdk.java.net/jdk/pull/5890/files/17da4f52..93e9ab77

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5890&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5890&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5890.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5890/head:pull/5890

PR: https://git.openjdk.java.net/jdk/pull/5890