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

[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.

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Commit messages:
 - Copyright
 - snprintf
 - cl analyze
 - Fix non-debug warning
 - Restore suppressions
 - Fix warnings
 - WIP: reenable awt warnings
 - Fix warnings

Changes: https://git.openjdk.org/jdk/pull/11841/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11841&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299592
  Stats: 185 lines in 11 files changed: 2 ins; 121 del; 62 mod
  Patch: https://git.openjdk.org/jdk/pull/11841.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11841/head:pull/11841

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