[ASan] Try to use a small (512 bytes) stack-local buffer in Report() for short messages, fall back to MmapOrDie() in the case of a failure.
This shall eliminate most of the cryptic "ERROR: failed to mmap" messages caused by recursively calling MmapOrDie() from MmapOrDie().


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@176802 91177308-0d34-0410-b5e6-96231b3b80d8