<AWT Dev> RFR: JDK-8260426: awt debug_mem.c DMem_AllocateBlock might leak memory

[Matthias Baesken]

It seems that the function DMem_AllocateBlock (debug_mem.c) has an early return that might lead to memory leaks.
See also the sonar issue Potential leak of memory pointed to by 'header' :
https://sonarcloud.io/project/issues?id=shipilev_jdk&languages=c&open=AXck8B7zBBG2CXpcngZM&resolved=false&severities=BLOCKER&types=BUG

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Commit messages:
 - JDK-8260426

Changes: https://git.openjdk.java.net/jdk/pull/2252/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2252&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260426
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2252.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2252/head:pull/2252

PR: https://git.openjdk.java.net/jdk/pull/2252