tests: Skip daemon-conf test if dir exceeds UNIX_PATH_MAX

The max path length for unix sockets is pretty small (108, see man 7 unix).
If 'make check' is run from a directory that exceeds this, one of the tests
will fail, and in such a way that requires manually editting the test to
determine why.

There are certainly other ways to handle this, but I've chosen just to skip
the offending test if we will exceed the length limitation.

v2: Drop bashism, use test infrastructure to warn and skip

tests/daemon-conf

@@ -76,6 +76,13 @@ sed 's,^log_outputs.*,log_outputs="3:file:'"$(pwd)/log"'",' tmp.conf > k \
     || fail=1
 mv k tmp.conf || fail=1
 
+# Unix socket max path size is 108 on linux. If the generated sock path
+# exceeds this, the test will fail, so skip it if CWD is too long
+SOCKPATH=`pwd`/libvirt-sock
+if test 108 -lt `echo $SOCKPATH | wc -c`; then
+    skip_test_ "CWD too long"
+fi
+
 $abs_top_builddir/daemon/libvirtd --pid-file=pid-file --config=tmp.conf > log 2>&1 & pid=$!
 sleep $sleep_secs
 kill $pid