[foreign-jextract] RFR: 8244128: Allocations larger than MAX_ALIGN can fail to be sliced to proper size.

[Jorn Vernee]

Hi,

This patch fixes a problem where the MemorySegment resulting from an allocation was not always sliced to the requested
size, when the allocation code was manually up-sizing the allocation in order to perform manual alignment of the
returned MemorySegment, but the initial allocation turned out to be aligned any ways.

Thanks,
Jorn

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Commit messages:
 - Slice allocated segments when alignedSize != byteSize (since alignedSize != buf might be false accidentally)

Changes: https://git.openjdk.java.net/panama-foreign/pull/136/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/136/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8244128
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/136.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/136/head:pull/136

PR: https://git.openjdk.java.net/panama-foreign/pull/136