[TableGen] Ensure that __lsan_is_turned_off isn't removed by DCE in llvm-tblgen

Summary:
Since asan is linked dynamically on Darwin, the weak interface symbol
is removed by -Wl,-dead_strip.

Reviewers: kcc, compnerd, aaron.ballman

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D37636

llvm-svn: 312914

llvm/utils/TableGen/TableGen.cpp

@@ -217,6 +217,6 @@ int main(int argc, char **argv) {
 #include <sanitizer/lsan_interface.h>
 // Disable LeakSanitizer for this binary as it has too many leaks that are not
 // very interesting to fix. See compiler-rt/include/sanitizer/lsan_interface.h .
-int __lsan_is_turned_off() { return 1; }
+LLVM_ATTRIBUTE_USED int __lsan_is_turned_off() { return 1; }
 #endif  // __has_feature(address_sanitizer)
 #endif  // defined(__has_feature)