private_syms: add virLogFilterListFree to libvirt_private.syms

Commit 660468b1 forgot to add it, so let's add it now to prevent future linker
issues.
Signed-off-by: NErik Skultety <eskultet@redhat.com>

src/libvirt_private.syms

@@ -1872,6 +1872,7 @@ virLockSpaceReleaseResourcesForOwner;
 virLogDefineFilter;
 virLogDefineOutput;
 virLogFilterFree;
+virLogFilterListFree;
 virLogGetDefaultPriority;
 virLogGetFilters;
 virLogGetNbFilters;