[ASan] Due to data races, ASan malloc stats are inaccurate, which may cause certain ASan interface functions returning negative values (casted to unsigned). Return a reasonable value if such a case is detected.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@166548 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed