[TSan] Fix comment describing shadow memory layout

[yln]

compiler-rt/lib/tsan/rtl/tsan_platform.h

75

This is the value in question, right?

compiler-rt/lib/tsan/rtl/tsan_platform.h

 };
 
 /*
 C/C++ on linux/x86_64 and freebsd/x86_64
 0000 0000 1000 - 0080 0000 0000: main binary and/or MAP_32BIT mappings (512GB)
 0040 0000 0000 - 0100 0000 0000: -
 0100 0000 0000 - 1000 0000 0000: shadow
 1000 0000 0000 - 3000 0000 0000: -
-3000 0000 0000 - 4000 0000 0000: metainfo (memory blocks and sync objects)
-4000 0000 0000 - 5500 0000 0000: -
[phone] - 3400 0000 0000: metainfo (memory blocks and sync objects)
[phone] - 5500 0000 0000: -
 5500 0000 0000 - 5680 0000 0000: pie binaries without ASLR or on 4.1+ kernels
 5680 0000 0000 - 7d00 0000 0000: -
 7b00 0000 0000 - 7c00 0000 0000: heap
 7c00 0000 0000 - 7e80 0000 0000: -
 7e80 0000 0000 - 8000 0000 0000: modules and main thread stack
 
 C/C++ on netbsd/amd64 can reuse the same mapping:
  * The address space starts from 0x1000 (option with 0x0) and ends with
    0x7f7ffffff000.
  * LoAppMem-kHeapMemEnd can be reused as it is.
  * No VDSO support.
  * No MidAppMem region.
  * No additional HeapMem region.
  * HiAppMem contains the stack, loader, shared libraries and heap.
  * Stack on NetBSD/amd64 has prereserved 128MB.
  * Heap grows downwards (top-down).
  * ASLR must be disabled per-process or globally.
 */
 struct Mapping48AddressSpace {
   static const uptr kMetaShadowBeg = 0x300000000000ull;
   static const uptr kMetaShadowEnd = 0x340000000000ull;
   static const uptr kShadowBeg     = 0x010000000000ull;
   static const uptr kShadowEnd = 0x100000000000ull;
   static const uptr kHeapMemBeg    = 0x7b0000000000ull;
   static const uptr kHeapMemEnd    = 0x7c0000000000ull;
   static const uptr kLoAppMemBeg   = 0x000000001000ull;
   static const uptr kLoAppMemEnd   = 0x008000000000ull;
   static const uptr kMidAppMemBeg  = 0x550000000000ull;
   static const uptr kMidAppMemEnd  = 0x568000000000ull;