blockdev: Give drives internal linkage

This is the list of drives defined with drive_init().  Hide it, so it
doesn't get abused.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

blockdev.c

@@ -15,7 +15,7 @@
 #include "qemu-config.h"
 #include "sysemu.h"
 
-struct drivelist drives = QTAILQ_HEAD_INITIALIZER(drives);
+static QTAILQ_HEAD(drivelist, DriveInfo) drives = QTAILQ_HEAD_INITIALIZER(drives);
 
 QemuOpts *drive_add(const char *file, const char *fmt, ...)
 {

blockdev.h

@@ -36,8 +36,6 @@ typedef struct DriveInfo {
 #define MAX_IDE_DEVS	2
 #define MAX_SCSI_DEVS	7
 
-extern QTAILQ_HEAD(drivelist, DriveInfo) drives;
-
 extern DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit);
 extern DriveInfo *drive_get_by_id(const char *id);
 extern int drive_get_max_bus(BlockInterfaceType type);