basic/iovec-wrapper: drop unused code

All non-test users iovec_wrapper define the struct as a field in a
bigger structure, so we never free it individually. Let's simplify the
code and assume it is never null.

src/basic/iovec-wrapper.c

@@ -7,10 +7,6 @@
 #include "iovec-wrapper.h"
 #include "string-util.h"
 
-struct iovec_wrapper *iovw_new(void) {
-        return new0(struct iovec_wrapper, 1);
-}
-
 void iovw_done(struct iovec_wrapper *iovw) {
         assert(iovw);
 
@@ -27,22 +23,6 @@ void iovw_done_free(struct iovec_wrapper *iovw) {
         iovw_done(iovw);
 }
 
-struct iovec_wrapper *iovw_free_free(struct iovec_wrapper *iovw) {
-        if (!iovw)
-                return NULL;
-
-        iovw_done_free(iovw);
-        return mfree(iovw);
-}
-
-struct iovec_wrapper *iovw_free(struct iovec_wrapper *iovw) {
-        if (!iovw)
-                return NULL;
-
-        iovw_done(iovw);
-        return mfree(iovw);
-}
-
 int iovw_put(struct iovec_wrapper *iovw, void *data, size_t len) {
         assert(iovw);
 
@@ -118,8 +98,7 @@ void iovw_rebase(struct iovec_wrapper *iovw, void *old, void *new) {
 }
 
 size_t iovw_size(const struct iovec_wrapper *iovw) {
-        if (!iovw)
-                return 0;
+        assert(iovw);
 
         return iovec_total_size(iovw->iovec, iovw->count);
 }

src/basic/iovec-wrapper.h

@@ -8,12 +8,6 @@ struct iovec_wrapper {
         size_t count;
 };
 
-struct iovec_wrapper *iovw_new(void);
-struct iovec_wrapper *iovw_free(struct iovec_wrapper *iovw);
-struct iovec_wrapper *iovw_free_free(struct iovec_wrapper *iovw);
-
-DEFINE_TRIVIAL_CLEANUP_FUNC(struct iovec_wrapper*, iovw_free_free);
-
 void iovw_done_free(struct iovec_wrapper *iovw);
 void iovw_done(struct iovec_wrapper *iovw);