added more extern C markers to keep as muh of the libraries C

src/render.h

@@ -4,6 +4,7 @@
 #ifdef __cplusplus
 extern "C" {
 #endif
+
 #include "context.h"
 
 typedef int depth_t;
@@ -74,5 +75,4 @@ extern void set_active_view(const view_t* view);
 #ifdef __cplusplus
 }
 #endif
-
 #endif /* _render_h */