Fixing Aravis support compilation issue

cmake/OpenCVFindLibsVideo.cmake

@@ -127,6 +127,8 @@ endif(WITH_GIGEAPI)
 # --- Aravis SDK ---
 ocv_clear_vars(HAVE_ARAVIS_API)
 if(WITH_ARAVIS)
+  check_module(glib-2.0 HAVE_ARAVIS_GLIB VIDEOIO)
+  if(HAVE_ARAVIS_GLIB)
     find_path(ARAVIS_INCLUDE_PATH "arv.h"
               PATHS /usr/local /var /opt /usr ENV ProgramFiles ENV ProgramW6432
               PATH_SUFFIXES include "aravis-0.6" "aravis-0.4"
@@ -135,6 +137,9 @@ if(WITH_ARAVIS)
     if(ARAVIS_LIBRARIES AND ARAVIS_INCLUDE_PATH)
       set(HAVE_ARAVIS_API TRUE)
     endif()
+  else()
+    message("Can not build Aravis support without glib2")
+  endif()
 endif(WITH_ARAVIS)
 
 # --- Dc1394 ---