revert adjusting of the BLOCKMAP boundaries to match the Vanilla algo

Although this was done in the Vanilla algorithm, it doesn't match
what's done in the algorithms used by MBF and Boom - and thus PrBoom+
which uses the latter. This fixes sync for one demo reported by
galileo31dos01 on 5L1C.wad MAP01.

src/doom/p_blockmap.c

@@ -46,9 +46,11 @@ void P_CreateBlockMap(void)
 	  maxy = vertexes[i].y >> FRACBITS;
     }
 
+#if 0
   // [crispy] doombsp/DRAWING.M:175-178
   minx -= 8; miny -= 8;
   maxx += 8; maxy += 8;
+#endif
 
   // Save blockmap parameters