tests: use a fixed NBD TLS certificate path

The default NBD TLS certificate path varies based on prefix given to
configure, causing tests to fail depending on build options.
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

tests/qemuxml2argvdata/disk-drive-network-tlsx509.args

@@ -44,8 +44,8 @@ file.server.host=192.168.0.3,file.server.port=9999,format=raw,if=none,\
 id=drive-virtio-disk2,serial=eb90327c-8302-4725-9e1b-4e85ed4dc252,cache=none \
 -device virtio-blk-pci,bus=pci.0,addr=0x6,drive=drive-virtio-disk2,\
 id=virtio-disk2 \
--object tls-creds-x509,id=objvirtio-disk3_tls0,dir=/etc/pki/qemu,\
-endpoint=client,verify-peer=yes \
+-object tls-creds-x509,id=objvirtio-disk3_tls0,dir=/etc/pki/libvirt-nbd/dummy,,\
+path,endpoint=client,verify-peer=yes \
 -drive file.driver=nbd,file.server.type=inet,file.server.host=example.com,\
 file.server.port=1234,file.tls-creds=objvirtio-disk3_tls0,format=raw,if=none,\
 id=drive-virtio-disk3,cache=none \

tests/qemuxml2argvtest.c

@@ -655,6 +655,9 @@ mymain(void)
     VIR_FREE(driver.config->vxhsTLSx509certdir);
     if (VIR_STRDUP_QUIET(driver.config->vxhsTLSx509certdir, "/etc/pki/libvirt-vxhs/dummy,path") < 0)
         return EXIT_FAILURE;
+    VIR_FREE(driver.config->nbdTLSx509certdir);
+    if (VIR_STRDUP_QUIET(driver.config->nbdTLSx509certdir, "/etc/pki/libvirt-nbd/dummy,path") < 0)
+        return EXIT_FAILURE;
 
     VIR_FREE(driver.config->hugetlbfs);
     if (VIR_ALLOC_N(driver.config->hugetlbfs, 2) < 0)
@@ -2860,6 +2863,7 @@ mymain(void)
     if (getenv("LIBVIRT_SKIP_CLEANUP") == NULL)
         virFileDeleteTree(fakerootdir);
 
+    VIR_FREE(driver.config->nbdTLSx509certdir);
     qemuTestDriverFree(&driver);
     VIR_FREE(fakerootdir);
     VIR_FREE(capslatest_x86_64);