Bug 572581: Fix uninit field access

MIExpressionsTest.testNestedBaseChildrenBug accesses this field like
this -data-evaluate-expression "*((((*(class Base*) this)).pNested))"
which, as pNested isn't init, can cause a Cannot access memory at
address 0x0 error.

Change-Id: Ie6ba01be3499df6e72e714bc5c02dcd5355468bf

dsf-gdb/org.eclipse.cdt.tests.dsf.gdb/data/launch/src/ExpressionTestApp.cc

@@ -78,6 +78,7 @@ public:
   BaseTest() {}
   void test() { 
     nested = 8;
+    pNested = &nested;
     return; 
   }
   Base Base; // make sure we don't get confused by the same name