RFR: JDK-8298093: improve cleanup and error handling of awt_parseColorModel in awt_parseImage.c [v2]

[Matthias Baesken]

> The cleanup and error handling in function awt_parseColorModel in awt_parseImage.c could be improved.

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  move freeing into awt_parseColorModel

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11508/files
  - new: https://git.openjdk.org/jdk/pull/11508/files/a5de4c0a..9b9f56ea

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11508&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11508&range=00-01

  Stats: 17 lines in 1 file changed: 8 ins; 1 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/11508.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11508/head:pull/11508

PR: https://git.openjdk.org/jdk/pull/11508