Use the stopsign as icon for timeouts and exceeded log-limits

When I browse failed builds in a jobset-eval on Hydra, I regularly
mistake actual build-failures with temporary issues like timeouts (that
probably disappear at the next eval).

To prevent this kind of issue, I figured that using the stopsign-svg for
builds with timeouts or exceeded log-limits is a reasonable choice for
the following reasons:

* A user can now distinguish between actual build-errors (like
  compilation-failures or oversized outputs) and (usually) temporary issues
  (like a bloated log or a timeout).

* The stopsign is also used for aborted jobs that are shown in a
  different tab and can't be confused with timeouts for that reason.

src/root/common.tt

@@ -229,9 +229,9 @@ BLOCK renderBuildStatusIcon;
     [% ELSIF buildstatus == 6 %]
       <img src="[% c.uri_for("/static/images/emojione-red-x-274c.svg") %]" height="[% size %]" width="[% size %]" title="Failed with output" alt="Failed with output" class="build-status" />
     [% ELSIF buildstatus == 7 %]
-      <img src="[% c.uri_for("/static/images/emojione-red-x-274c.svg") %]" height="[% size %]" width="[% size %]" title="Timed out" alt="Timed out" class="build-status" />
+      <img src="[% c.uri_for("/static/images/emojione-stopsign-1f6d1.svg") %]" height="[% size %]" width="[% size %]" title="Timed out" alt="Timed out" class="build-status" />
     [% ELSIF buildstatus == 10 %]
-      <img src="[% c.uri_for("/static/images/emojione-red-x-274c.svg") %]" height="[% size %]" width="[% size %]" title="Log limit exceeded" alt="Log limit exceeded" class="build-status" />
+      <img src="[% c.uri_for("/static/images/emojione-stopsign-1f6d1.svg") %]" height="[% size %]" width="[% size %]" title="Log limit exceeded" alt="Log limit exceeded" class="build-status" />
     [% ELSIF buildstatus == 11 %]
       <img src="[% c.uri_for("/static/images/emojione-red-x-274c.svg") %]" height="[% size %]" width="[% size %]" title="Output size limit exceeded" alt="Output size limit exceeded" class="build-status" />
     [% ELSIF buildstatus == 12 %]