misc: fix build on absence of magic.h

If magic.h is not present, there will be unresolved references to the magic_t
type in plausible.c. Fix that by moving the protecting #ifdef directive.

Signed-off-by: Artemiy Volkov <artemiyv@acm.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/misc/plausible.c b/misc/plausible.c
index aea4fce..00bc6e2 100644
--- a/misc/plausible.c
+++ b/misc/plausible.c
@@ -36,12 +36,12 @@
 #include "nls-enable.h"
 #include "blkid/blkid.h"
 
+#ifdef HAVE_MAGIC_H
 static magic_t (*dl_magic_open)(int);
 static const char *(*dl_magic_file)(magic_t, const char *);
 static int (*dl_magic_load)(magic_t, const char *);
 static void (*dl_magic_close)(magic_t);
 
-#ifdef HAVE_MAGIC_H
 #ifdef HAVE_DLOPEN
 #include <dlfcn.h>