[foreign-jextract] RFR: 8252465: jextract generates wrong layout and varhandle when different structs have same named field [v2]

[Athijegannathan Sundararajan]

> all tests pass. all samples jextract and run fine on Mac.

Athijegannathan Sundararajan has updated the pull request incrementally with one additional commit since the last
revision:

  forgot to add test.

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/295/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/295/files/552bc8ea..68592725

Webrevs:
 - full: https://webrevs.openjdk.java.net/panama-foreign/295/webrev.01
 - incr: https://webrevs.openjdk.java.net/panama-foreign/295/webrev.00-01

  Stats: 80 lines in 2 files changed: 80 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/295.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/295/head:pull/295

PR: https://git.openjdk.java.net/panama-foreign/pull/295