net: move tap_set_sndbuf() to tap-linux.c

TUNSETSNDBUF is only available on linux

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/net/tap-solaris.c b/net/tap-solaris.c
index 0dd5b68..de5855a 100644
--- a/net/tap-solaris.c
+++ b/net/tap-solaris.c
@@ -183,3 +183,8 @@
     fcntl(fd, F_SETFL, O_NONBLOCK);
     return fd;
 }
+
+int tap_set_sndbuf(int fd, QemuOpts *opts)
+{
+    return 0;
+}