Make CPU and memory thread-safe

src/memory/memory.c

@@ -2,8 +2,10 @@
 #include "vriscv.h"
 
 uint8_t* memory;
+pthread_mutex_t memory_mutex;
 
 void mem_init()
 {
     memory = malloc(memory_size);
+    pthread_mutex_init(&memory_mutex, 0);
 }

src/memory/memory.h

@@ -2,8 +2,10 @@
 #define MEMORY_H
 
 #include <stdint.h>
+#include <pthread.h>
 
 extern uint8_t* memory;
+extern pthread_mutex_t memory_mutex;
 
 void mem_init();