warning message if clock is too far off

git-svn-id: https://bitcoin.svn.sourceforge.net/svnroot/bitcoin/trunk@141 1a98c847-1fd6-4fd8-948a-caf3550aa51b

util.h

@@ -143,6 +143,7 @@ extern char pszSetDataDir[MAX_PATH];
 extern bool fShutdown;
 extern bool fDaemon;
 extern bool fCommandLine;
+extern string strWarning;
 
 void RandAddSeed();
 void RandAddSeedPerfmon();
@@ -298,6 +299,11 @@ inline int64 roundint64(double d)
     return (int64)(d > 0 ? d + 0.5 : d - 0.5);
 }
 
+inline int64 abs64(int64 n)
+{
+    return (n >= 0 ? n : -n);
+}
+
 template<typename T>
 string HexStr(const T itbegin, const T itend, bool fSpaces=true)
 {