tar: move FNM_LEADING_DIR #define to tar.c - no other users.

Closes bug 1332.

archival/tar.c

@@ -28,6 +28,11 @@
 #include "libbb.h"
 #include "unarchive.h"
 
+/* FIXME: Stop using this non-standard feature */
+#ifndef FNM_LEADING_DIR
+#define FNM_LEADING_DIR 0
+#endif
+
 #define block_buf bb_common_bufsiz1
 
 #if ENABLE_FEATURE_TAR_CREATE

include/platform.h

@@ -268,12 +268,6 @@ static ALWAYS_INLINE char* strchrnul(const char *s, char c)
 # define lchown chown
 #endif
 
-/* THIS SHOULD BE CLEANED OUT OF THE TREE ENTIRELY */
-/* FIXME: fix tar.c! */
-#ifndef FNM_LEADING_DIR
-#define FNM_LEADING_DIR 0
-#endif
-
 #if (defined __digital__ && defined __unix__)
 #include <standards.h>
 #define HAVE_STANDARDS_H