[foreign-jextract] RFR: 8262733: jextract generates clashing names which results in compilation error with javac

[Athijegannathan Sundararajan]

name clash is avoided by checking surrounding class names

-------------

Commit messages:
 - 8262733: jextract generates clashing names which results in compilation error with javac

Changes: https://git.openjdk.java.net/panama-foreign/pull/462/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=462&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262733
  Stats: 66 lines in 3 files changed: 57 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/462.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/462/head:pull/462

PR: https://git.openjdk.java.net/panama-foreign/pull/462