reuse a single size alignment implementation

util.h

@@ -1,6 +1,7 @@
 #ifndef UTIL_H
 #define UTIL_H
 
+#include <stddef.h>
 #include <stdint.h>
 
 // C11 noreturn doesn't work in C++
@@ -32,6 +33,11 @@ static inline int ffzl(unsigned long x) {
     return __builtin_ffsl(~x);
 }
 
+static inline size_t align(size_t size, size_t align) {
+    size_t mask = align - 1;
+    return (size + mask) & ~mask;
+}
+
 COLD noreturn void fatal_error(const char *s);
 
 typedef uint8_t u8;