Qt: add conditional compilation in switches.

Compiling without pcap, the lack of all the cases causes an error.

../ui/qt/main_window_slots.cpp:756:13: error: enumeration values 'Capture',
'Update', and 'Fixed' not handled in switch [-Werror,-Wswitch]
    switch (ev->captureContext()) {
            ^
1 error generated.

Change-Id: I36c0bc854b1d864ebf54ac59ca15743918bc7d2b
Reviewed-on: https://code.wireshark.org/review/25127
Reviewed-by: Roland Knall <rknall@gmail.com>
Petri-Dish: Roland Knall <rknall@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Dario Lombardo <lomato@gmail.com>

ui/qt/capture_file.h

@@ -40,9 +40,11 @@ class CaptureEvent : public QObject
     Q_OBJECT
 public:
     enum Context {
+#ifdef HAVE_LIBPCAP
         Capture =  0x0001,
         Update =   0x0100 | Capture,
         Fixed =    0x0200 | Capture,
+#endif
         File =     0x0002,
         Reload =   0x0100 | File,
         Rescan =   0x0200 | File,

ui/qt/main_status_bar.cpp

@@ -649,6 +649,7 @@ void MainStatusBar::captureEventHandler(CaptureEvent * ev)
 {
     switch(ev->captureContext())
     {
+#ifdef HAVE_LIBPCAP
     case CaptureEvent::Update:
         switch ( ev->eventType() )
         {
@@ -669,6 +670,7 @@ void MainStatusBar::captureEventHandler(CaptureEvent * ev)
             break;
         }
         break;
+#endif
     case CaptureEvent::Save:
         switch ( ev->eventType() )
         {

ui/qt/wireshark_application.cpp

@@ -1334,6 +1334,7 @@ void WiresharkApplication::captureEventHandler(CaptureEvent * ev)
 {
     switch(ev->captureContext())
     {
+#ifdef HAVE_LIBPCAP
     case CaptureEvent::Update:
     case CaptureEvent::Fixed:
         switch ( ev->eventType() )
@@ -1350,6 +1351,7 @@ void WiresharkApplication::captureEventHandler(CaptureEvent * ev)
             break;
         }
         break;
+#endif
     case CaptureEvent::File:
         switch ( ev->eventType() )
         {