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/libs/glsl/glsl.pri

@@ -1,2 +1 @@
 LIBS *= -l$$qtLibraryName(GLSL)
-DEFINES *= QT_CREATOR

src/libs/glsl/glsl.pro

@@ -1,8 +1,7 @@
 TEMPLATE = lib
 TARGET = GLSL
 DEFINES += \
-    GLSL_BUILD_LIB \
-    QT_CREATOR
+    GLSL_BUILD_LIB
 
 include(../../qtcreatorlibrary.pri)
 include(glsl-lib.pri)

src/libs/glsl/glsl.qbs

@@ -5,7 +5,6 @@ QtcLibrary {
     name: "GLSL"
 
     cpp.defines: base.concat([
-        "QT_CREATOR",
         "GLSL_BUILD_LIB"
     ])