[foreign-jextract] RFR: 8237573: Add a basic call overhead benchmark

[Jorn Vernee]

Hi,

Per my earlier email [1], this PR adds some basic call overhead benchmarks.

2 benchmarks are added:
- CallOverhead, which measures both an empty and an identity function call.
- PointsDistance, which extends the existing points benchmarks with one that measures the distance between 2 points doing
  the calculation is C (using a native call).

The latter also shows the difference between passing a pointer to a struct, vs passing a struct by value,
PointsDistance.panama_MemoryAddress and PointsDistance.panama_MemorySegment respectively.

This acts as a basis to test the coming performance improvements in this area.

Thanks,
Jorn

[1] : https://mail.openjdk.java.net/pipermail/panama-dev/2020-March/008007.html

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Commit messages:
 - Fix more carriage returns + tabs
 - Remove carriage returns
 - newline at end of files
 - Add basic call overhead benchmarks

Changes: https://git.openjdk.java.net/panama-foreign/pull/65/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/65/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8237573
  Stats: 398 lines in 9 files changed: 391 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/65.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/65/head:pull/65

PR: https://git.openjdk.java.net/panama-foreign/pull/65