TranslateClauseWithTerminator: Avoid unbound read of word array (#2104)

src/libespeak-ng/translate.c

 				num_wtab[j].flags &= ~(FLAG_MULTIPLE_SPACES | FLAG_EMBEDDED); // don't use these flags for subsequent parts when splitting a number
 
 			// include the next few characters, in case there are an ordinal indicator or other suffix
-			memcpy(pn, pw, 16);
+			strncpy(pn, pw, 16);
 			pn[16] = 0;
 			nw = 0;