Implement ProgressManager's progress-bar-on-icon on Windows 7.

Allow compiling with older Windows SDKs, link ole32 explictly.
If you want this feature to work, you need to compile and test
it on Windows 7.

Task-Number: QTCREATORBUG-252

src/plugins/coreplugin/coreplugin.pro

@@ -168,6 +168,7 @@ RESOURCES += core.qrc \
 
 win32 {
     SOURCES += progressmanager/progressmanager_win.cpp
+    LIBS += -lole32
 }
 else:macx {
     OBJECTIVE_SOURCES += progressmanager/progressmanager_mac.mm