[compiler-rt] [msan][aarch64] mallinfo interceptor (PR #73728)

[Thurston Dang via llvm-commits]

thurstond wrote:

AFAICS the interceptor zeros out the struct - which is enough to pass compiler-rt/test/msan/Linux/mallinfo.cpp, because it only tests that the struct is unpoisoned, not the actual contents - but doesn't actually give any useful info. Do any apps need the real info?

https://github.com/llvm/llvm-project/pull/73728