Tests: fixed invocation of has_daemon().

mp4.t

diff --git a/mp4.t b/mp4.t
index 57ec1ca..c6096cb 100644
--- a/mp4.t
+++ b/mp4.t
@@ -23,7 +23,8 @@
 select STDERR; $| = 1;
 select STDOUT; $| = 1;
 
-my $t = Test::Nginx->new()->has(qw/http mp4/)->has_daemon('ffprobe ffmpeg')
+my $t = Test::Nginx->new()->has(qw/http mp4/)->has_daemon('ffprobe')
+	->has_daemon('ffmpeg')
 	->plan(14)->write_file_expand('nginx.conf', <<'EOF');
 
 %%TEST_GLOBALS%%