Use a StringRef. No functionality change.
[sanitizer] Fix build with _FILE_OFFSET_BITS=64.

Sanitizer source is not affected by _FILE_OFFSET_BITS in general,
but this one file must be built with 32-bit off_t. More details in the code.
R600: Use default GlobalDirective

The overridden one wasn't inserting a space,
so you would end up with .globalfoo