Avoid rebuilding the RTSanitizerCommon objects when building clang_rt.san.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@182218 91177308-0d34-0410-b5e6-96231b3b80d8
[sanitizer] factor out ByteMap from SizeClassAllocator32 so that it can be later replaced with a more memory-efficient implementation on 64-bit.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@182234 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan] Remove an unused ChunkBase field

Also fix wrong alignment maths and an outdated comment

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@182238 91177308-0d34-0410-b5e6-96231b3b80d8