[Sanitizer] Move OS-specific code for MemoryMappingLayout into separate source files.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@198003 91177308-0d34-0410-b5e6-96231b3b80d8
[Sanitizer] Teach MemoryMappingLayout to dump all loaded modules.

Use this to implement GetListOfModules() on Mac and on Android
(on Linux we use dl_iterate_phdr).


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@198004 91177308-0d34-0410-b5e6-96231b3b80d8