make: use the more modern wchar routines, not widec.h

*** 123,133 ****
                      ) {
                          continue;
                  }
                  INIT_STRING_FROM_STACK(value, buffer);          
                  expand_value(p->value, &value, false);
!                 if ((length = wslen(value.buffer.start)) >= MAXPATHLEN) {
                          mbs = tmp_mbs_buffer = getmem((length + 1) * MB_LEN_MAX);
                          (void) wcstombs(mbs,
                                          value.buffer.start,
                                          (length + 1) * MB_LEN_MAX);
                  } else {
--- 123,133 ----
                      ) {
                          continue;
                  }
                  INIT_STRING_FROM_STACK(value, buffer);          
                  expand_value(p->value, &value, false);
!                 if ((length = wcslen(value.buffer.start)) >= MAXPATHLEN) {
                          mbs = tmp_mbs_buffer = getmem((length + 1) * MB_LEN_MAX);
                          (void) wcstombs(mbs,
                                          value.buffer.start,
                                          (length + 1) * MB_LEN_MAX);
                  } else {