buildsys: Move usb redir cflags/libs to per object

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170907082918.7299-10-famz@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Fam Zheng <famz@redhat.com>
diff --git a/configure b/configure
index a620465..d8455d4 100755
--- a/configure
+++ b/configure
@@ -4235,8 +4235,6 @@
         usb_redir="yes"
         usb_redir_cflags=$($pkg_config --cflags libusbredirparser-0.5)
         usb_redir_libs=$($pkg_config --libs libusbredirparser-0.5)
-        QEMU_CFLAGS="$QEMU_CFLAGS $usb_redir_cflags"
-        libs_softmmu="$libs_softmmu $usb_redir_libs"
     else
         if test "$usb_redir" = "yes"; then
             feature_not_found "usb-redir" "Install usbredir devel"
@@ -5793,6 +5791,8 @@
 
 if test "$usb_redir" = "yes" ; then
   echo "CONFIG_USB_REDIR=y" >> $config_host_mak
+  echo "USB_REDIR_CFLAGS=$usb_redir_cflags" >> $config_host_mak
+  echo "USB_REDIR_LIBS=$usb_redir_libs" >> $config_host_mak
 fi
 
 if test "$opengl" = "yes" ; then