[RFR] [11u] 8224851: AArch64: fix warnings and errors with Clang and GCC 8.3

[Andrew John Hughes]

Webrev: https://cr.openjdk.java.net/~andrew/openjdk11/8224851/webrev.01/
Bug: https://bugs.openjdk.java.net/browse/JDK-8224851

Backporting this fix helps to get OpenJDK 11 building with GCC 10. With
11.0.6, it fails due to  MacroAssembler::call_VM_leaf_base being
declared twice.

The backport is mostly clean. The only changes were due to an older
copyright header in src/hotspot/cpu/aarch64/frame_aarch64.cpp and the
lack of the simulator conditionals in
src/hotspot/os_cpu/linux_aarch64/os_linux_aarch64.cpp, thanks to its
removal in JDK-8228400.

Ok for 11.0.7?

Thanks,
-- 
Andrew :)

Senior Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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