bpo-38730: Remove usage of stpncpy as it's not supported on MSVC 2008. (GH-17081)

Author: benjaminp

Objects/structseq.c

@@ -252,7 +252,12 @@ structseq_repr(PyStructSequence *obj)
  }
 
 /* "typename(", limited to TYPE_MAXSIZE */
-pbuf=stpncpy(pbuf, typ->tp_name, TYPE_MAXSIZE);
+len=strlen(typ->tp_name);
+if (len>TYPE_MAXSIZE) {
+len=TYPE_MAXSIZE;
+ }
+pbuf=memcpy(pbuf, typ->tp_name, len);
+pbuf+=len;
 *pbuf++='(';
 
 for (i=0; i<VISIBLE_SIZE(obj); i++) {