RFR: 8304290: Some JNI calls made without checking exceptions in media [v2]

[Alexander Matveev]

> - Added missing exception checks for JNI calls.
>  - Improved JNI error checking by checking for both exception and return value.
>  - Minor code clean up.

Alexander Matveev has updated the pull request incrementally with one additional commit since the last revision:

  8304290: Some JNI calls made without checking exceptions in media [v2]

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1094/files
  - new: https://git.openjdk.org/jfx/pull/1094/files/0f8bd616..582daf7e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1094&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1094&range=00-01

  Stats: 14 lines in 3 files changed: 0 ins; 0 del; 14 mod
  Patch: https://git.openjdk.org/jfx/pull/1094.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1094/head:pull/1094

PR: https://git.openjdk.org/jfx/pull/1094