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>

configure

@@ -4235,8 +4235,6 @@ if test "$usb_redir" != "no" ; then
         usb_redir="yes"
         usb_redir_cflags=$($pkg_config --cflags libusbredirparser-0.5)
         usb_redir_libs=$($pkg_config --libs libusbredirparser-0.5)
-        QEMU_CFLAGS="$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 @@ fi
 
 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

hw/usb/Makefile.objs

@@ -38,6 +38,8 @@ endif
 
 # usb redirection
 common-obj-$(CONFIG_USB_REDIR) += redirect.o quirks.o
+redirect.o-cflags = $(USB_REDIR_CFLAGS)
+redirect.o-libs = $(USB_REDIR_LIBS)
 
 # usb pass-through
 ifeq ($(CONFIG_LIBUSB)$(CONFIG_USB),yy)