Bridge testing gap on AArch64

I'm filing this to help organize and drive work to finish big missing pieces on AArch64 in the test suite. There are about 140 tests on x86 that are not ported to AArch64, resulting in a big gap in coverage. As we run larger A64 apps we're running into many bugs, at least some of which would have been caught and fixed much more easily on our test suite than on a large, complex, custom app.

Xref the old master porting issue #1569 for AArch64 (and i#1551 for ARM).

My main initial focus is drcachesim, and there we have two big drivers of missing tests:

• 11 tests missing because of toolchain linking issue #2007 (closed)
• 4 tests missing because of lack of annotation support #1672, but we don't really need annotations: we could tweak the test app