do not actually build examples in production builds

-developer-build enables an actual build of examples, based on the
assumption that developers want to test it (it can be still disabled
with -nomake examples). regular users otoh want only the examples
sources installed.

Change-Id: Ifc6a108099929175a3960480802b271a758fdd38
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

mkspecs/features/qt_example_installs.prf

@@ -92,4 +92,12 @@ probase = $$relative_path($$_PRO_FILE_PWD_, $$dirname(_QMAKE_CONF_)/examples)
         allfiles -= doc
         !isEmpty(allfiles): warning("remaining files in $$_PRO_FILE_PWD_: $$allfiles")
     }
+
+    # Do not actually build the examples in production builds
+    !equals(TEMPLATE, subdirs):!contains(QT_CONFIG, private_tests) {
+        TEMPLATE = aux
+        CONFIG -= have_target qt staticlib dll
+        SOURCES =
+        INSTALLS -= target
+    }
 }