[asan] Move the "coverage" flag to common flags.

The implementation lives in sanitizer_common and will need to access that flag.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@208566 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan tests] Use the proper attribute on RunStrChrTest helper functions to avoid "unused function" warnings

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@208568 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan tests] Also define USED/UNUSED in lib/sanitizer_common/sanitizer_internal_defs.h if Clang is used on Windows

Otherwise we end up with macro redefinition warnings

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@208571 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan tests] Don't run FakeStack.CreateDestroy on Windows as it OOMs

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@208572 91177308-0d34-0410-b5e6-96231b3b80d8