configure: rename $confdir to $qemu_confdir

There's no "confdir" variable on Autoconf, but it's good to make it
clear that it's a variable for the Qemu-specific subdirectory inside
$sysconfdir.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

configure

@@ -2879,7 +2879,7 @@ if test "$mingw32" = "yes" ; then
     done
 fi
 
-confdir=$sysconfdir$confsuffix
+qemu_confdir=$sysconfdir$confsuffix
 
 tools=
 if test "$softmmu" = yes ; then
@@ -3025,7 +3025,7 @@ echo "mandir=$mandir" >> $config_host_mak
 echo "datadir=$qemu_datadir" >> $config_host_mak
 echo "sysconfdir=$sysconfdir" >> $config_host_mak
 echo "docdir=$qemu_docdir" >> $config_host_mak
-echo "confdir=$confdir" >> $config_host_mak
+echo "confdir=$qemu_confdir" >> $config_host_mak
 echo "libexecdir=\${prefix}/libexec" >> $config_host_mak
 echo "CONFIG_QEMU_SHAREDIR=\"$prefix$datasuffix\"" >> $config_host_mak
 echo "CONFIG_QEMU_HELPERDIR=\"$prefix/libexec\"" >> $config_host_mak