xputsl: fix the *other* line in this function :-)

Some of the grep tests were still failing because we weren't flushing
stdout --- xflush takes a bool that says whether to actually flush, so
we need to pass 1, not 0.

Author: enh-google

lib/xwrap.c

@@ -159,7 +159,7 @@ void xprintf(char *format, ...)
 // Put string with length (does not append newline)
 void xputsl(char *s, int len)
 {
-  xflush(0);
+  xflush(1);
   xwrite(1, s, len);
 }