Honor -nomake for examples and demos

Don't build or install demos and examples when they are disabled.

Reviewed-by: TrustMe
(cherry picked from commit 61c0b5c3)

qtdeclarative.pro

@@ -10,10 +10,16 @@ module_qtdeclarative_tools.depends = module_qtdeclarative_src
 module_qtdeclarative_demos.subdir = demos
 module_qtdeclarative_demos.target = module-qtdeclarative-demos
 module_qtdeclarative_demos.depends = module_qtdeclarative_src
+!contains(QT_BUILD_PARTS,demos) {
+    module_qtdeclarative_demos.CONFIG = no_default_target no_default_install
+}
 
 module_qtdeclarative_examples.subdir = examples/declarative
 module_qtdeclarative_examples.target = module-qtdeclarative-examples
 module_qtdeclarative_examples.depends = module_qtdeclarative_src
+!contains(QT_BUILD_PARTS,examples) {
+    module_qtdeclarative_examples.CONFIG = no_default_target no_default_install
+}
 
 module_qtdeclarative_tests.subdir = tests
 module_qtdeclarative_tests.target = module-qtdeclarative-tests