Invert logic and fix bad copy/paste

QGCExternalLibs.pri

@@ -54,6 +54,8 @@ contains (CONFIG, QGC_DISABLE_APM_MAVLINK) {
     message("Disable APM MAVLink support")
     DEFINES += NO_ARDUPILOT_DIALECT
     CONFIG  += ArdupilotDisabled
+} else {
+    CONFIG  += ArdupilotEnabled
 }
 
 # First we select the dialect, checking for valid user selection

qgroundcontrol.pro

@@ -961,16 +961,18 @@ SOURCES += \
         src/VehicleSetup/PX4FirmwareUpgradeThread.cc \
 }}
 
-# ArduPilot FirmwarePlugin
+# ArduPilot Specific
 
-!ArdupilotDisabled {
-    INCLUDEPATH += \
+ArdupilotEnabled {
+    HEADERS += \
         src/Settings/APMMavlinkStreamRateSettings.h \
 
     SOURCES += \
         src/Settings/APMMavlinkStreamRateSettings.cc \
 }
 
+# ArduPilot FirmwarePlugin
+
 APMFirmwarePlugin {
     RESOURCES *= src/FirmwarePlugin/APM/APMResources.qrc