fdc: always compile-check debug prints

Coverity noticed that some variables are only used by debug prints, and
called them unused. Always compile the print statements. While we're
here, print to stderr as well.

Bonus: Fix a debug printf I broke in f31937aaSigned-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
[Touched up commit message. --js]
Message-id: 1454971529-14830-1-git-send-email-jsnow@redhat.com

hw/block/fdc.c

@@ -41,14 +41,15 @@
 
 /********************************************************/
 /* debug Floppy devices */
-//#define DEBUG_FLOPPY
 
-#ifdef DEBUG_FLOPPY
+#define DEBUG_FLOPPY 0
+
 #define FLOPPY_DPRINTF(fmt, ...)                                \
-    do { printf("FLOPPY: " fmt , ## __VA_ARGS__); } while (0)
-#else
-#define FLOPPY_DPRINTF(fmt, ...)
-#endif
+    do {                                                        \
+        if (DEBUG_FLOPPY) {                                     \
+            fprintf(stderr, "FLOPPY: " fmt , ## __VA_ARGS__);   \
+        }                                                       \
+    } while (0)
 
 /********************************************************/
 /* Floppy drive emulation                               */
@@ -353,7 +354,7 @@ static int pick_geometry(FDrive *drv)
             parse = &fd_formats[size_match];
             FLOPPY_DPRINTF("User requested floppy drive type '%s', "
                            "but inserted medium appears to be a "
-                           "%d sector '%s' type\n",
+                           "%"PRId64" sector '%s' type\n",
                            FloppyDriveType_lookup[drv->drive],
                            nb_sectors,
                            FloppyDriveType_lookup[parse->drive]);