Extend the type of argument and return value of V1L_Write

This allows adding up to ssize_t chunks

bin/varnishd/cache/cache.h

@@ -964,7 +964,7 @@ void V1L_EndChunk(const struct worker *w);
 void V1L_Reserve(struct worker *, struct ws *, int *fd, struct vsl_log *, double t0);
 unsigned V1L_Flush(const struct worker *w);
 unsigned V1L_FlushRelease(struct worker *w);
-unsigned V1L_Write(const struct worker *w, const void *ptr, int len);
+size_t V1L_Write(const struct worker *w, const void *ptr, ssize_t len);
 
 /* cache_range.c [VRG] */
 void VRG_dorange(struct req *req, struct busyobj *bo, const char *r);

bin/varnishd/http1/cache_http1_line.c

@@ -221,8 +221,8 @@ V1L_Flush(const struct worker *wrk)
 	return (v1l->werr);
 }
 
-unsigned
-V1L_Write(const struct worker *wrk, const void *ptr, int len)
+size_t
+V1L_Write(const struct worker *wrk, const void *ptr, ssize_t len)
 {
 	struct v1l *v1l;