Build integrityhid support only if it is available

Change-Id: I6e0aa2f74516d4c0a1905b188f195834d395584b
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

src/plugins/platforms/integrity/integrity.pro

@@ -8,13 +8,18 @@ QT += \
 SOURCES = \
     main.cpp \
     qintegrityfbintegration.cpp \
-    qintegrityfbscreen.cpp \
-    qintegrityhidmanager.cpp
+    qintegrityfbscreen.cpp
 
 HEADERS = \
     qintegrityfbintegration.h \
-    qintegrityfbscreen.h \
-    qintegrityhidmanager.h
+    qintegrityfbscreen.h
+
+qtConfig(integrityhid) {
+    SOURCES += \
+        qintegrityhidmanager.cpp
+    HEADERS += \
+        qintegrityhidmanager.h
+}
 
 OTHER_FILES += integrity.json