parse-util: fix conversion from size_t on s390 (#3147)

On s390 size_t is an unsigned long, nor an unsigned int. They both are
of the same size and can be cast to each other safely, but the compiler
still seems unhappy about incompatible pointers.

Fixes: 7c2da2ca8

src/basic/parse-util.h

@@ -93,7 +93,7 @@ static inline int safe_atoli(const char *s, long int *ret_u) {
 #if SIZE_MAX == UINT_MAX
 static inline int safe_atozu(const char *s, size_t *ret_u) {
         assert_cc(sizeof(size_t) == sizeof(unsigned));
-        return safe_atou(s, ret_u);
+        return safe_atou(s, (unsigned *) ret_u);
 }
 #else
 static inline int safe_atozu(const char *s, size_t *ret_u) {