define QT_CREATOR centrally

numerous "3rdparty" libraries have respective #ifdefs, and consequently
the define is added in several places. it's quite a mess with the .pr?
and .qbs files, though. solve the problem by sidestepping it.

Change-Id: I5a6b1ba7cfe96b44f0a4f4ef9738900906a44316
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/qmljseditor/qmljseditor.pro

@@ -4,8 +4,7 @@ include(../../qtcreatorplugin.pri)
 QT += script
 
 DEFINES += \
-    QMLJSEDITOR_LIBRARY \
-    QT_CREATOR
+    QMLJSEDITOR_LIBRARY
 
 HEADERS += \
     qmljseditor.h \

src/plugins/qmljseditor/qmljseditor.qbs

@@ -17,7 +17,6 @@ QtcPlugin {
     Depends { name: "CPlusPlus" }
 
     Depends { name: "cpp" }
-    cpp.defines: base.concat("QT_CREATOR")
 
     files: [
         "QmlJSEditor.mimetypes.xml",