Fix an issue we hit 1 in 1000 times.

Turns out, that because the name consumption is fairly lax (often lots
of excess space after the name, etc) we were reading 2 too many bytes
(because we weren't taken the length of the leaf off the available
length).  This would error when it so happened that a structure was at
the end of the type list and we'd read past the end of the tpi stream.

volatility/framework/symbols/windows/mspdb.py

@@ -722,6 +722,7 @@ class PdbReader:
             module.get_enumeration("LEAF_TYPE"), layer_name = module._layer_name, offset = offset)
         consumed = leaf_type.vol.base_type.size
         offset += consumed
+        length -= consumed
 
         if leaf_type in [
                 leaf_type.LF_CLASS, leaf_type.LF_CLASS_ST, leaf_type.LF_STRUCTURE, leaf_type.LF_STRUCTURE_ST,