devel/qemu: Add support to build VDE if installed.

Check is the VDE development package is installed and if it is
enabled support.

source-builder/config/qemu-1-1.cfg

@@ -40,6 +40,12 @@ BuildRoot: %{_tmppath}/%{name}-root-%(%{__id_u} -n)
   mkdir -p ${build_dir}
   cd ${build_dir}
 
+  %if %{pkgconfig check vdeplug}
+    VDE_CONFIG="--enable-vde"
+    VDE_CFLAGS="%{pkgconfig cflags vdeplug}"
+    VDE_LDFLAGS="%{pkgconfig ldflags vdeplug} %{pkgconfig libs vdeplug}"
+  %endif
+
   %{host_build_flags}
 
   if test "%{_build}" != "%{_host}" ; then
@@ -48,18 +54,26 @@ BuildRoot: %{_tmppath}/%{name}-root-%(%{__id_u} -n)
 
   SYSROOT=$SB_TMPPREFIX
 
+  #
+  # The --extra-cflags and --extra-ldflags do not work as expected.
+  #
   PKG_CONFIG_PATH=$SYSROOT/lib/pkgconfig \
   PKG_CONFIG_BUILD_TOP_DIR=$SB_TMPROOT \
   %{_ld_library_path}=$SYSROOT/lib \
-  LDFLAGS="-Wl,-rpath -Wl,/$SB_PREFIX_CLEAN/lib" \
+  LDFLAGS="-Wl,-rpath -Wl,/$SB_PREFIX_CLEAN/lib ${VDE_LDFLAGS}" \
+  CFLAGS="${CFLAGS} ${VDE_CFLAGS}" \
   ../${source_dir_qemu}/configure \
     --prefix=%{_prefix} \
     ${CROSS_PREFIX_OPTION} \
     --make=%{__make} \
+    ${VDE_CONFIG} \
     --disable-werror \
     --disable-tools \
     --disable-pie \
     --disable-vnc \
+    --disable-sdl \
+    --disable-gtk \
+    --disable-opengl \
     --disable-netmap
 
   %{_ld_library_path}=$SYSROOT/lib \