[scudo] Secondary Cache Dump

Dumped some basic info about what is being cached and about the cache
itself. Output of test below:

...
Stats: MapAllocatorCache: EntriesCount: 33, MaxEntriesCount: 64, MaxEntrySize: 1048576
StartBlockAddress: 0x6d342c1000, EndBlockAddress: 0x6d342d2000, BlockSize: 69632
StartBlockAddress: 0x6fc45ff000, EndBlockAddress: 0x6fc462f000, BlockSize: 196608
...

Reviewed By: Chia-hungDuan

Differential Revision: https://reviews.llvm.org/D153483