HelpPlugin: Compile fix for msvc2010

Make sure that help/helpmanager.h is before coreplugin/helpmanager.h
in the INCLUDEPATH.

src/plugins/help/help.pro

@@ -2,6 +2,8 @@ TEMPLATE = lib
 TARGET = Help
 QT += network
 
+INCLUDEPATH += $$PWD
+
 include(../../qtcreatorplugin.pri)
 include(help_dependencies.pri)
 
@@ -58,8 +60,6 @@ FORMS += docsettingspage.ui \
     generalsettingspage.ui \
     remotehelpfilter.ui
 
-INCLUDEPATH += $$PWD
-
 RESOURCES += help.qrc
 include(../../shared/help/help.pri)