A dynamic recompiler block's validity is now separate from its starting code address, should fix most of the known recompiler fatals;

The CD-ROM buffer is now dynamically malloc'd;
Did a lot of bugfixing in cdrom.c and scsi_disk.c, Debian 8's modprobe aha1542 and the NT 3.10.404.1 Trantor 310b driver now work;
Fixed the IDE IRQ/MIRQ mess and ATAPI DMA transfer length;
Fixed the operation of mmutranslate() a bit;
Commented out several instances of excess logging;
Applied the mainline PCem commit prefetch commit;
Readded missing Sound Blaster DSP MIDI behavior and gave it the correct MPU struct;
All non-IBM 486 machines now correctly have the VLB flag set.

src/cpu/codegen.h

@@ -55,7 +55,9 @@ typedef struct codeblock_t
         
         int pnt;
         int ins;
-        
+
+	int valid;
+
         int was_recompiled;
         int TOP;