RFR: 8289743: AArch64: Clean up patching logic [v10]

[Andrew Haley]

> The current logic for patching is a mess of if-then-elses. By rearranging the logic and using a switch we can make it both easier to understand and faster.

Andrew Haley has updated the pull request incrementally with one additional commit since the last revision:

  8289743: AArch64: Clean up patching logic

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9398/files
  - new: https://git.openjdk.org/jdk/pull/9398/files/458a1ff8..c9eb876d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9398&range=09
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9398&range=08-09

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/9398.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9398/head:pull/9398

PR: https://git.openjdk.org/jdk/pull/9398