[foreign-jextract] RFR: 8252634: jextract should generate type annotations for C types [v2]

[Athijegannathan Sundararajan]

> @C annotation generated for C types

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

  Incorporating review changes. Expanded test cases, removed excess copyright, renamed variable for clarity.
  Left a FIXME for function pointer visitor.

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/300/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/300/files/a8744715..fbbb279c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=300&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=300&range=00-01

  Stats: 121 lines in 4 files changed: 60 ins; 41 del; 20 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/300.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/300/head:pull/300

PR: https://git.openjdk.java.net/panama-foreign/pull/300