asan: fix format string in CHECK


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@172203 91177308-0d34-0410-b5e6-96231b3b80d8
asan: improve the benchmark


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@172209 91177308-0d34-0410-b5e6-96231b3b80d8