RFR: 7903132: Replace casts with type test pattern [v3]

[Ethan McCue]

> Replaces a handful of casts following type tests with the equivalent pattern syntax.
> 
> I cannot create a matching issue, as I do not have an account on the bug tracker.

Ethan McCue has updated the pull request incrementally with one additional commit since the last revision:

  Use patterns inline with && expression when possible for equals

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

Changes:
  - all: https://git.openjdk.java.net/jextract/pull/5/files
  - new: https://git.openjdk.java.net/jextract/pull/5/files/12c04e17..63e2aa7a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jextract&pr=5&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jextract&pr=5&range=01-02

  Stats: 22 lines in 4 files changed: 1 ins; 9 del; 12 mod
  Patch: https://git.openjdk.java.net/jextract/pull/5.diff
  Fetch: git fetch https://git.openjdk.java.net/jextract pull/5/head:pull/5

PR: https://git.openjdk.java.net/jextract/pull/5