Fix extern declaration

src/foreign/from_cache_esi_deliver.h

@@ -30,9 +30,9 @@
 
 #include <limits.h>
 
-const struct vdp vped_pretend_gz;
-const struct vdp vped_gzgz;
-const struct vdp vped_ved;
+extern const struct vdp vped_pretend_gz;
+extern const struct vdp vped_gzgz;
+extern const struct vdp vped_ved;
 
 struct nexus_gzip {
 	unsigned		magic;

src/pesi.c

@@ -47,6 +47,8 @@
 #include "pesi.h"
 
 /* shared with vmod code */
+extern struct lock stats_lock;
+extern struct VSC_pesi *stats;
 struct lock stats_lock;
 struct VSC_pesi *stats = NULL;
 

src/vdp_pesi.c

@@ -82,6 +82,7 @@ static void assert_vdp_next_not(struct req *, const struct vdp *);
 
 /* shared with vmod code */
 struct VSC_lck *lck_bytes_tree, *lck_pesi_tree;
+extern struct mempool *mempool;
 struct mempool *mempool = NULL;
 
 /* also used by our version of cache_esi_deliver.c */