Add infamous #ifdef __cplusplus idiom

src/libsm64.h

@@ -15,6 +15,10 @@
     #define SM64_LIB_FN
 #endif
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct SM64Surface
 {
     int16_t type;
@@ -186,4 +190,8 @@ extern SM64_LIB_FN void sm64_play_sound(int32_t soundBits, float *pos);
 extern SM64_LIB_FN void sm64_play_sound_global(int32_t soundBits);
 extern SM64_LIB_FN void sm64_set_sound_volume(float vol);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif//LIB_SM64_H

test/main.cpp

@@ -9,8 +9,9 @@
 #include <unistd.h>
 #include <pthread.h>
 
-extern "C" {
 #include "../src/libsm64.h"
+
+extern "C" {
 #define SDL_MAIN_HANDLED
 #include "level.h"
 #include "context.h"