Fix order of includes in Windows-specific files

These files assume, that WIN32 is defined by compiler or MSVC project
file, when in MSYS2 and MinGW environments, it is defined in config.h
and appears after dosbox.h is included, which in turn is included by
associated header (cdrom.h in this case).

Fixes: #42

src/dos/cdrom_aspi_win32.cpp

@@ -16,13 +16,12 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
+#include "cdrom.h"
 
 #if defined (WIN32)
 
 #include <ctype.h>
 
-#include "dosbox.h"
-#include "cdrom.h"
 #include "support.h"
 
 //Are actually system includes but leave for now

src/dos/cdrom_image.cpp

@@ -16,6 +16,8 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
+#include "cdrom.h"
+
 // #define DEBUG 1
 #ifdef DEBUG
 #include <time.h> // time_t, tm, time(), and localtime()
@@ -37,7 +39,6 @@
 #include <string.h>
 #endif
 
-#include "cdrom.h"
 #include "drives.h"
 #include "support.h"
 #include "setup.h"

src/dos/cdrom_ioctl_win32.cpp

@@ -16,6 +16,7 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
+#include "cdrom.h"
 
 #if defined (WIN32)
 
@@ -35,8 +36,6 @@
 
 #include <mmsystem.h>
 
-#include "cdrom.h"
-
 // for a more sophisticated implementation of the mci cdda functionality
 // see the SDL sources, which the mci_ functions are based on