[master] RFR: Fix loading Klass* in C1 on AArch64

[Roman Kennke]

PR #20 was not quite correct on AArch64:
- We cannot push/pop r0 in the code stub, because we must not mess with SP there, otherwise the argument passing does not work.
- We should use far_call() and not far_jump(), so that the return comes back into the stub, and not to the continuation (or whereever LR points to).

Testing:
 - [x] tier1
 - [ ] tier2
 - [ ] tier3

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Commit messages:
 - Fix loading Klass* in C1 on AArch64

Changes: https://git.openjdk.java.net/lilliput/pull/34/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lilliput&pr=34&range=00
  Stats: 15 lines in 1 file changed: 11 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/lilliput/pull/34.diff
  Fetch: git fetch https://git.openjdk.java.net/lilliput pull/34/head:pull/34

PR: https://git.openjdk.java.net/lilliput/pull/34