[sanitizer_common] Define SANITIZER_WEAK_IMPORT for Go race detector (#186525)
Currently, when building the Go race detector (when SANITIZER_GO
is set), SANITIZER_WEAK_IMPORT is no-op. It is perfectly fine to
define SANITIZER_WEAK_IMPORT for Go just like other cases. That
will tell the Go linker to treat _dyld_get_dyld_header as a weak
import.
Perhaps SANITIZER_WEAK_ATTRIBUTE can also be defined for Go. That
would be a separate patch.