add C++ guards

include/ucore/mersenne_twister.h

@@ -1,6 +1,9 @@
 #ifndef UCORE_MERSENNE_TWISTER_H
 #define UCORE_MERSENNE_TWISTER_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 /** Context used for the PRNG*/
 #define MT_RAND_N 624
@@ -23,5 +26,9 @@ void mtsrand(int seed, MTRand *r);
  */
 unsigned int mtrand(MTRand *r);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif