[asan] asan_allocator2: fix the memalign handling (clear the first word of allocated chunk in case there is an old memalign magic)
[asan] asan_allocator2: fix the memalign handling (clear the first word of allocated chunk in case there is an old memalign magic)

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@172603 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt