tests: Allow use of close() in mock libraries

As mock libraries are not to be linked against libvirt, the
sc_prohibit_close syntax-check rule does not apply.

This fixes a syntax-check failure introduced by commit a03cbfe0.

cfg.mk

@@ -1158,7 +1158,7 @@ exclude_file_name_regexp--sc_prohibit_strdup = \
   ^(docs/|examples/|src/util/virstring\.c|tests/vir(netserverclient|cgroup)mock.c$$)
 
 exclude_file_name_regexp--sc_prohibit_close = \
-  (\.p[yl]$$|\.spec\.in$$|^docs/|^(src/util/virfile\.c|src/libvirt-stream\.c|tests/vir(cgroup|pci)mock\.c)$$)
+  (\.p[yl]$$|\.spec\.in$$|^docs/|^(src/util/virfile\.c|src/libvirt-stream\.c|tests/vir.+mock\.c)$$)
 
 exclude_file_name_regexp--sc_prohibit_empty_lines_at_EOF = \
   (^tests/(qemuhelp|nodeinfo|virpcitest)data/|\.diff$$)