[Sanitizer] Rename InternalVector to InternalMmapVector

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@183972 91177308-0d34-0410-b5e6-96231b3b80d8
[LSan] Use a typedef for frontier vector

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@183973 91177308-0d34-0410-b5e6-96231b3b80d8