Remove the DirectShow backend

It's been deprecated by Microsoft since quite some time.
We should only have one backend on Windows, and then WMF
seems to be the correct one. WMF is missing features
like Camera, so some additional implementation work on
WMF will be required.

Change-Id: I5c3db4020b130efa78575c9da116a8ae6c34f7a1
Reviewed-by: Doris Verria <doris.verria@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

config_help.txt

@@ -5,4 +5,4 @@ Multimedia options:
   -no-gstreamer ........ Disable support for GStreamer
   -gstreamer [version] . Enable GStreamer support [auto]
                          With no parameter, 1.0 is tried first, then 0.10.
-  -evr ................. Enables EVR in DirectShow and WMF [auto]
+  -evr ................. Enables EVR in WMF [auto]

src/multimedia/configure.json

@@ -10,7 +10,6 @@
         "options": {
             "alsa": "boolean",
             "evr": { "type": "boolean" },
-            "directshow": { "type": "boolean" },
             "wmf": { "type": "boolean" },
             "gstreamer": { "type": "optionalString", "values": [ "no", "yes" ] },
             "pulseaudio": "boolean"
@@ -32,13 +31,6 @@
                 { "libs": "-framework AVFoundation -framework Foundation" }
             ]
         },
-        "directshow": {
-            "label": "DirectShow",
-            "test": "directshow",
-            "sources": [
-                { "libs": "-lstrmiids -ldmoguids -luuid -lmsdmo -lole32 -loleaut32" }
-            ]
-        },
         "gstreamer_1_0": {
             "label": "GStreamer 1.0",
             "export": "gstreamer",
@@ -131,11 +123,6 @@
             "label": "wmsdk.h",
             "type": "compile",
             "test": "wmsdk"
-        },
-        "wshellitem": {
-            "label": "WShellItem",
-            "type": "compile",
-            "test": "wshellitem"
         }
     },
 
@@ -151,11 +138,6 @@
             "condition": "libs.avfoundation",
             "output": [ "feature", "privateFeature" ]
         },
-        "directshow": {
-            "label": "DirectShow",
-            "condition": "config.win32 && libs.directshow",
-            "output": [ "feature", "privateFeature" ]
-        },
         "evr": {
             "label": "evr.h",
             "condition": "config.win32 && tests.evr",
@@ -219,11 +201,6 @@
             "condition": "config.win32 && tests.wmsdk",
             "output": [ "privateFeature" ]
         },
-        "wshellitem": {
-            "label": "WShellItem",
-            "condition": "config.win32 && features.directshow && tests.wshellitem",
-            "output": [ "feature", "privateFeature" ]
-        },
         "wmf": {
             "label": "Windows Media Foundation",
             "condition": "config.win32 && libs.wmf",
@@ -244,7 +221,6 @@
                 "pulseaudio",
                 "mmrenderer",
                 "avfoundation",
-                "directshow",
                 "wmf"
             ]
         }