Merge #77: Add missing include

08443c4 Add missing include (Cory Fields)

Pull request description:

  stdint is needed for uint64_t and friends. Discovered when testing pre-compiled headers, which disturbs usual include ordering.

  The problem can be seen with the simple testcase:

  src/bad.cpp:
  ```c++
  #include "int_utils.h"
  int main(){}
  ```
  ```g++ bad.cpp -o bad.o```

ACKs for top commit:
  sipa:
    ACK 08443c4
  fanquake:
    ACK 08443c4

Tree-SHA512: ffa134738dfb43207c8487d3e3f1a76fedce98f4087b3d3b636274283b65b9a037ce0ce5ce94133131bb98416790ff11c981500a3b717f6b2201e773ead5d583

Author: sipa

src/int_utils.h

@@ -7,6 +7,7 @@
 #ifndef _MINISKETCH_INT_UTILS_H_
 #define _MINISKETCH_INT_UTILS_H_
 
+#include <stdint.h>
 #include <stdlib.h>
 
 #include <limits>