RFR: 7903158: jextract crashes due to name clash with pointer to function typedefs [v2]

[Athijegannathan Sundararajan]

> suffixing $ like it is done already for exception variable in the same source file. Piggybacking to remove unused jtreg header is another test

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

  fixing the names of lambda params to use "_" prefix instead (review comment)

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Changes:
  - all: https://git.openjdk.java.net/jextract/pull/21/files
  - new: https://git.openjdk.java.net/jextract/pull/21/files/22b75d9b..a224637e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jextract&pr=21&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jextract&pr=21&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jextract/pull/21.diff
  Fetch: git fetch https://git.openjdk.java.net/jextract pull/21/head:pull/21

PR: https://git.openjdk.java.net/jextract/pull/21