vp10: add extern "C" to headers

Change-Id: Ie2e8b37fa01ce8d6b993684f431f3159d511cfb1
diff --git a/vp10/encoder/resize.h b/vp10/encoder/resize.h
index 131fc80..bf63770 100644
--- a/vp10/encoder/resize.h
+++ b/vp10/encoder/resize.h
@@ -14,6 +14,10 @@
 #include <stdio.h>
 #include "vpx/vpx_integer.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void vp10_resize_plane(const uint8_t *const input,
                       int height,
                       int width,
@@ -121,4 +125,9 @@
                                 int owidth,
                                 int bd);
 #endif    // CONFIG_VP9_HIGHBITDEPTH
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
 #endif    // VP10_ENCODER_RESIZE_H_