Override wxApp::OnAssertFailure in L7Test.

We do nothing in this override.

wxASSERT_MSG would fail in LGridJsonCellRenderer::ProcessJsonValue and
in XmlHelper::ValidateXmlValue called by
LGridXmlCellRenderer::ProcessXmlValue. This happens with postgresql
only, when the corresponding database value is empty. The cell value
is set to [Invalid], and next rendering leads to a crash in debug build
only.
Why does wxASSERT_MSG fail? Why with postgresql and not with sqlite?

L7Test/nbproject/private/configurations.xml

@@ -13,6 +13,8 @@
         <gdb_interceptlist>
           <gdbinterceptoptions gdb_all="false" gdb_unhandled="true" gdb_unexpected="true"/>
         </gdb_interceptlist>
+        <gdb_signals>
+        </gdb_signals>
         <gdb_options>
           <DebugOptions>
           </DebugOptions>
@@ -47,8 +49,6 @@
         <gdb_interceptlist>
           <gdbinterceptoptions gdb_all="false" gdb_unhandled="true" gdb_unexpected="true"/>
         </gdb_interceptlist>
-        <gdb_signals>
-        </gdb_signals>
         <gdb_options>
           <DebugOptions>
           </DebugOptions>