find_first_of returns npos, which is a size_t.

Index: src/util.cpp
--- src/util.cpp.orig
+++ src/util.cpp
@@ -5,5 +5,7 @@
 
 extern "C" {
+#include <stddef.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <X11/Xlib.h>
 }
@@ -59,7 +61,7 @@ string Util::truncate(string str, char c) {
 
 string Util::canonicalDir(string path) {
     string dir = canonicalPath(path);
-    unsigned int pos = 0;
+    size_t pos = 0;
 
     pos = dir.find_last_of('/');
     if (pos != string::npos) {
@@ -123,7 +125,7 @@ string Util::encodeEscapes(string str) {
 string Util::lastToken(string str, char delim) {
 
     string result = "";
-    unsigned int pos = str.find_last_of(delim);
+    size_t pos = str.find_last_of(delim);
 
     if (pos != string::npos) {
         result = str.substr(pos + 1, str.length() - pos);
@@ -381,7 +383,7 @@ string Util::shortenString(string str, unsigned int n)
 
 set<string> Util::stringSplit(string s, string delimiter){
     set<string> res;
-    unsigned int pos = 0;
+    size_t pos = 0;
     while (pos != string::npos){
         pos = s.find_first_of(delimiter);
         res.insert(s.substr(0, pos));