[libvirt] [PATCH] build: mark conditionally unused variables

[Eric Blake]

These fixes solve a compilation failure on FreeBSD:

util/virnetdevtap.c: In function 'virNetDevTapGetName':
util/virnetdevtap.c:56: warning: unused parameter 'tapfd' [-Wunused-parameter]
util/virnetdevtap.c:56: warning: unused parameter 'ifname' [-Wunused-parameter]

* src/util/virnetdevtap.c (virNetDevTapGetName): Add attributes
when TUNGETIFF is not present.

Signed-off-by: Eric Blake <eblake at redhat.com>
---

Pushing under the build-breaker rule.

 src/util/virnetdevtap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/util/virnetdevtap.c b/src/util/virnetdevtap.c
index fac95ec..7d77f81 100644
--- a/src/util/virnetdevtap.c
+++ b/src/util/virnetdevtap.c
@@ -53,7 +53,7 @@
  * Returns 0 if the interface name is successfully queried, -1 otherwise
  */
 int
-virNetDevTapGetName(int tapfd, char **ifname)
+virNetDevTapGetName(int tapfd ATTRIBUTE_UNUSED, char **ifname ATTRIBUTE_UNUSED)
 {
 #ifdef TUNGETIFF
     struct ifreq ifr;
-- 
1.8.1.4