[foreign-jextract] RFR: 8240811: jextract generates non-compilable code for name collision between a struct and a global variable

[Athijegannathan Sundararajan]

names are mangled when there are collisions.

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Commit messages:
 - 8240811: jextract generates non-compilable code for name collision between a struct and a global variable

Changes: https://git.openjdk.java.net/panama-foreign/pull/44/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/44/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8240811
  Stats: 245 lines in 5 files changed: 224 ins; 8 del; 13 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/44.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/44/head:pull/44

PR: https://git.openjdk.java.net/panama-foreign/pull/44