* tests/scripts/features/output-sync: increase test timeout.

I'm getting random failures with a timeout of 10s; increase to 30s.
diff --git a/tests/scripts/features/output-sync b/tests/scripts/features/output-sync
index 7139e00..7237e65 100644
--- a/tests/scripts/features/output-sync
+++ b/tests/scripts/features/output-sync
@@ -53,6 +53,8 @@
 
 @syncfiles = qw(mksync.foo mksync.foo_start mksync.bar mksync.bar_start);
 
+$tmout = 30;
+
 output_sync_clean();
 mkdir('foo', 0777);
 mkdir('bar', 0777);
@@ -140,7 +142,7 @@
 bar: end
 baz: start
 baz: end
-#MAKE#[1]: Leaving directory '#PWD#/bar'\n", 0, 10);
+#MAKE#[1]: Leaving directory '#PWD#/bar'\n", 0, $tmout);
 
 # Test per-target synchronization.
 # Note we have to sleep again here after starting the foo makefile before
@@ -171,7 +173,7 @@
 #MAKE#[1]: Entering directory '#PWD#/bar'
 baz: start
 baz: end
-#MAKE#[1]: Leaving directory '#PWD#/bar'\n", 0, 10);
+#MAKE#[1]: Leaving directory '#PWD#/bar'\n", 0, $tmout);
 
 # Rerun but this time suppress the directory tracking
 unlink(@syncfiles);
@@ -183,7 +185,7 @@
 foo: start
 foo: end
 baz: start
-baz: end\n", 0, 10);
+baz: end\n", 0, $tmout);
 
 # Test that messages from make itself are enclosed with
 # "Entering/Leaving directory" messages.
@@ -236,7 +238,7 @@
 #MAKE#[1]: Leaving directory '#PWD#/bar'
 #MAKE#[1]: Entering directory '#PWD#/foo'
 foo: end
-#MAKE#[1]: Leaving directory '#PWD#/foo'\n", 0, 10);
+#MAKE#[1]: Leaving directory '#PWD#/foo'\n", 0, $tmout);
 
 
 # Remove temporary directories and contents.