runtime: fix missing newline when dumping bad symbol table

If the symbol table isn't sorted, we print it and abort.  However, we
were missing the line break after each symbol, resulting in one
gigantic line instead of a nicely formatted table.

Change-Id: Ie5c6f3c256d0e648277cb3db4496512a79d266dd
Reviewed-on: https://go-review.googlesource.com/1182
Reviewed-by: Russ Cox <rsc@golang.org>