[compiler-rt][asan][hwasan] Fix Android bots

Fix failure in Android bots from refactoring in
5d2be1a1 (https://crbug.com/1106482).

We need to make the UnmapFromTo available outside sanitizer_common for
calls from hwasan and asan linux handling. While here, remove
declaration of GetHighMemEnd which is no longer in sanitizer_common.