BUG: Check for existence of fromstr which used in `fromstr_next_ele…

…ment` (numpygh-14174)

The check tested the wrong function. In principle a dtype could only implement one of the two slots/functions.

Fix numpy#14173.

numpy/core/src/multiarray/ctors.c

@@ -4000,7 +4000,7 @@ PyArray_FromString(char *data, npy_intp slen, PyArray_Descr *dtype,
         size_t nread = 0;
         char *end;
 
-        if (dtype->f->scanfunc == NULL) {
+        if (dtype->f->fromstr == NULL) {
             PyErr_SetString(PyExc_ValueError,
                             "don't know how to read "       \
                             "character strings with that "  \