Cleaned and slightly refactored stdio.h and file I/O syscalls

include/c/stdint.h

@@ -1,7 +1,7 @@
 #ifndef STDINT_H
 #define STDINT_H
 
-#define NULL ((void*)0)
+#include <stddef.h>
 
 // Signed ints
 typedef signed char int8_t;
@@ -15,7 +15,6 @@ typedef unsigned short uint16_t;
 typedef unsigned int uint32_t;
 typedef unsigned long long uint64_t;
 
-// Other
-typedef unsigned int size_t;
+// TODO: floats
 
 #endif