RFR: 8299592: Fix and reenable warnings in java.desktop native code compilation [v3]

[Daniel Jeliński]

> Please review this patch that fixes and re-enables a few warnings in libawt compilation.
> 
> Verified that debug and release builds finish successfully on Win, Mac and Linux. Also verified that client libs tests still pass.

Daniel Jeliński has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 10 commits:

 - Merge remote-tracking branch 'origin' into awt-warning-cleanup
 - Merge remote-tracking branch 'origin' into awt-warning-cleanup
 - Copyright
 - snprintf
 - cl analyze
 - Fix non-debug warning
 - Restore suppressions
 - Fix warnings
 - WIP: reenable awt warnings
 - Fix warnings

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Changes: https://git.openjdk.org/jdk/pull/11841/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11841&range=02
  Stats: 182 lines in 11 files changed: 1 ins; 120 del; 61 mod
  Patch: https://git.openjdk.org/jdk/pull/11841.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/11841/head:pull/11841

PR: https://git.openjdk.org/jdk/pull/11841