AArch64: use aarch64_be instead of arm64_be in all tests.

arm64_be doesn't really exist; it was useful for testing while AArch64 and
ARM64 were separate, but now the only real way to refer to the system is
aarch64_be.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@213747 91177308-0d34-0410-b5e6-96231b3b80d8
Prevent assert in ASTMatchFinder.

If nodes without memoization data (e.g. TypeLocs) are bound to specific
names, that effectively prevents memoization as those elements cannot be
compared effectively. If it is tried anyway, this can lead to an assert
as demonstrated in the new test.

In the long term, the better solution will be to enable DynTypedNodes
without memoization data. For now, simply skip memoization instead.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@213751 91177308-0d34-0410-b5e6-96231b3b80d8