Fully support old windows 8ib user space virtual memory

Addresses are converted in blocks(asan, automap, stack, ...), with the start and end addresses modified using (address & 0xffffff) | ((address >> 28) << 24).

Following addresses are only specified to frame accuracy with the last 4 hex digits chopped off.
null, loader, image and arena blocks have not been modified.
asan     [0x00007fff, 0x10007fff] ⇒ [0x00007fff, 0x01007fff] Not currently supported.
automap  [0x10008004, 0x1fe7fffb] ⇒ [0x01008004, 0x01e7fffb]
_mmi     [0x1fe7fffc, 0x1ffffffb] ⇒ [0x01e7fffc, 0x01fffffb] Listed as memtrack outside of the memtrack files.
fixedmap [0x30000004, 0x40000003] ⇒ [0x03000004, 0x04000003]
nsync    [0x6fc00004, 0x6fcffffb] ⇒ [0x06c00004, 0x06cffffb]
zipos    [0x6fd00004, 0x6fdffffb] ⇒ [0x06d00004, 0x06dffffb] I don't think this is used currently on the vista branch.
g_fds    [0x6fe00004, 0x6feffffb] ⇒ [0x06e00004, 0x06effffb]
winargs  [0x6ffffffe, 0x6fffffff] ⇒ [0x06fffffe, 0x06ffffff] Not entirely confident on if this is accurate.
stack    [0x70000000, 0x70000003] ⇒ [0x07000000, 0x07000003] Not entirely confident on if this is accurate.

This map is documented in memtrack64-8tib.txt with the original 128tib version renamed to memtrack64-128tib.txt.

Modified windows 8.1 check macro name to match existing windows 10 one.
Modified IsShadowFrame to correctly identify the asan block on old windows. Required as the asan block on 128tib virtual memory systems is larger than 2^43 - 1 and so all blocks were reporting as asan.

libc/calls/reservefd.c

@@ -41,7 +41,8 @@ static volatile size_t mapsize;
 /**
  * Grows file descriptor array memory if needed.
  *
- * @see libc/runtime/memtrack64.txt
+ * @see libc/runtime/memtrack64-128tib.txt
+ * @see libc/runtime/memtrack64-8tib.txt
  * @see libc/runtime/memtrack32.txt
  * @asyncsignalsafe
  */