meson: Replace empty configuration_data() with copy keyword

Use 'copy' keyword to avoid meson warning message.
Note that 'copy' keyword in configure_file() is available
since meson 0.47.0

https://bugzilla.gnome.org/show_bug.cgi?id=797298

gst/audiofx/meson.build

@@ -30,10 +30,10 @@ if have_orcc
 else
   orc_h = configure_file(input : orcsrc + '-dist.h',
     output : orcsrc + '.h',
-    configuration : configuration_data())
+    copy : true)
   orc_c = configure_file(input : orcsrc + '-dist.c',
     output : orcsrc + '.c',
-    configuration : configuration_data())
+    copy : true)
 endif
 
 gstaudiofx = library('gstaudiofx',

gst/deinterlace/meson.build

@@ -26,10 +26,10 @@ if have_orcc
 else
   orc_h = configure_file(input : orcsrc + '-dist.h',
     output : orcsrc + '.h',
-    configuration : configuration_data())
+    copy : true)
   orc_c = configure_file(input : orcsrc + '-dist.c',
     output : orcsrc + '.c',
-    configuration : configuration_data())
+    copy : true)
 endif
 
 gstdeinterlace = library('gstdeinterlace',

gst/videobox/meson.build

@@ -11,10 +11,10 @@ if have_orcc
 else
   orc_h = configure_file(input : orcsrc + '-dist.h',
     output : orcsrc + '.h',
-    configuration : configuration_data())
+    copy : true)
   orc_c = configure_file(input : orcsrc + '-dist.c',
     output : orcsrc + '.c',
-    configuration : configuration_data())
+    copy : true)
 endif
 
 gstvideobox = library('gstvideobox',

gst/videomixer/meson.build

@@ -16,10 +16,10 @@ if have_orcc
 else
   orc_h = configure_file(input : orcsrc + '-dist.h',
     output : orcsrc + '.h',
-    configuration : configuration_data())
+    copy : true)
   orc_c = configure_file(input : orcsrc + '-dist.c',
     output : orcsrc + '.c',
-    configuration : configuration_data())
+    copy : true)
 endif
 
 gstvideomixer = library('gstvideomixer',