libraries/libvirt: Fix build when qemu not present.

Signed-off-by: B. Watson <yalhcru@gmail.com>

Signed-off-by: Willy Sudiarto Raharjo <willysr@slackbuilds.org>

libraries/libvirt/libvirt.SlackBuild

@@ -133,8 +133,12 @@ sed -i \
   $PKG/etc/libvirt/qemu.conf
 
 # disable seccomp support or else VMs won't start with new libvirt/qemu combo
+# 20220212 bkw: this file doesn't exist if qemu wasn't installed. and
+# since qemu isn't in REQUIRES, it's optional, so the build shouldn't fail.
+if [ -e $PKG/etc/libvirt/qemu.conf ]; then
   sed -i  "s|^\#seccomp_sandbox = 1|seccomp_sandbox = 0|" \
     $PKG/etc/libvirt/qemu.conf
+fi
 
 find $PKG/usr/man -type f -exec gzip -9 {} \;
 for i in $( find $PKG/usr/man -type l ) ; do ln -s $( readlink $i ).gz $i.gz ; rm $i ; done