[wwwdocs] remove last use of cellspacing="0"

[Gerald Pfeifer]

We had this left on the main page.  I makes a slight visual difference,
but not signficant, and I plan on replacing the formatting via a table
mid term.

Applied.

Gerald

Index: style.mhtml
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/style.mhtml,v
retrieving revision 1.155
diff -u -r1.155 style.mhtml
--- style.mhtml	9 Sep 2018 21:18:17 -0000	1.155
+++ style.mhtml	15 Sep 2018 23:01:47 -0000
@@ -70,7 +70,7 @@
 
 <if <var-exists navigation>
  <group
-  <table class="border0" cellspacing="0">
+  <table class="border0">
   <tr>
 
   <td class="top border0">                                <!-- main frame -->