facedetect: Fix compiler warning with clang 3.8

Use namespace only after it was actually defined by a header.

gstfacedetect.cpp:79:17: error: using directive refers to implicitly-defined namespace 'std' [-Werror]
using namespace std;
                ^

diff --git a/ext/opencv/gstfacedetect.cpp b/ext/opencv/gstfacedetect.cpp
index 58d224f..3c82ce0 100644 (file)
--- a/ext/opencv/gstfacedetect.cpp
+++ b/ext/opencv/gstfacedetect.cpp
@@ -76,10 +76,10 @@
 #  include <config.h>
 #endif
 
-using namespace std;
-
 #include <vector>
 
+using namespace std;
+
 #include "gstfacedetect.h"
 #if (CV_MAJOR_VERSION >= 3)
 #include <opencv2/imgproc.hpp>