exynos: add C++ support to exynos_drmif header

Add the usual extern "C" when compiling in C++ mode.

Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

exynos/exynos_drmif.h

@@ -31,6 +31,10 @@
 #include <stdint.h>
 #include "exynos_drm.h"
 
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 struct exynos_device {
 	int fd;
 };
@@ -109,4 +113,8 @@ int exynos_handle_event(struct exynos_device *dev,
 				struct exynos_event_context *ctx);
 
 
+#if defined(__cplusplus)
+}
+#endif
+
 #endif /* EXYNOS_DRMIF_H_ */