buildsys: Move seccomp cflags/libs to per object

Like many other libraries, libseccomp cflags and libs should only apply
to the building of necessary objects. Do so in the usual way with the
help of per object variables.
Signed-off-by: Fam Zheng <famz@redhat.com>

Makefile.objs

@@ -70,6 +70,8 @@ common-obj-y += backends/
 common-obj-y += chardev/
 
 common-obj-$(CONFIG_SECCOMP) += qemu-seccomp.o
+qemu-seccomp.o-cflags := $(SECCOMP_CFLAGS)
+qemu-seccomp.o-libs := $(SECCOMP_LIBS)
 
 common-obj-$(CONFIG_FDT) += device_tree.o
 

configure

@@ -2035,8 +2035,8 @@ if test "$seccomp" != "no" ; then
 
     if test "$libseccomp_minver" != "" &&
        $pkg_config --atleast-version=$libseccomp_minver libseccomp ; then
-        libs_softmmu="$libs_softmmu $($pkg_config --libs libseccomp)"
-        QEMU_CFLAGS="$QEMU_CFLAGS $($pkg_config --cflags libseccomp)"
+        seccomp_cflags="$($pkg_config --cflags libseccomp)"
+        seccomp_libs="$($pkg_config --libs libseccomp)"
         seccomp="yes"
     else
         if test "$seccomp" = "yes" ; then
@@ -5829,6 +5829,8 @@ fi
 
 if test "$seccomp" = "yes"; then
   echo "CONFIG_SECCOMP=y" >> $config_host_mak
+  echo "SECCOMP_CFLAGS=$seccomp_cflags" >> $config_host_mak
+  echo "SECCOMP_LIBS=$seccomp_libs" >> $config_host_mak
 fi
 
 # XXX: suppress that