Fix out-of-tree compilation of widget examples

'styles' are only defined in the qt build internals, when the
examples are compiled inside a configured Qt source. That's not
the case for the examples e.g. in the Qt SDK.

(windows is a default style on all platforms, anyway. So I
think the check is superfluous in the first place.)

Task-number: QTBUG-36655
Change-Id: I7114619efd479408dad99c8514f8e33ddcab7c7c
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

examples/widgets/widgets/styles/styles.pro

@@ -7,8 +7,6 @@ SOURCES       = main.cpp \
                 widgetgallery.cpp
 RESOURCES     = styles.qrc
 
-REQUIRES += "contains(styles, windows)"
-
 # install
 target.path = $$[QT_INSTALL_EXAMPLES]/widgets/widgets/styles
 INSTALLS += target

examples/widgets/widgets/widgets.pro

@@ -16,6 +16,7 @@ SUBDIRS       = analogclock \
                 shapedclock \
                 sliders \
                 spinboxes \
+                styles \
                 stylesheet \
                 tablet \
                 tetrix \
@@ -23,5 +24,3 @@ SUBDIRS       = analogclock \
                 validators \
                 wiggly \
                 windowflags
-
-contains(styles, windows): SUBDIRS += styles