[foreign-jextract] RFR: 8239918: jextract generates uncompilable code for no argument C function

[Athijegannathan Sundararajan]

removing trailing comma when there are no arguments for the function.

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Commits:
 - 1891bc90: 8239918: jextract generates uncompilable code for no argument C function

Changes: https://git.openjdk.java.net/panama-foreign/pull/30/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/30/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8239918
  Stats: 113 lines in 4 files changed: 111 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/30.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/30/head:pull/30

PR: https://git.openjdk.java.net/panama-foreign/pull/30