Added a cast to stop the compilier from complaining about signed/unsigned mismatch

git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1508 726aef4b-f618-498e-8847-2d620e286838

DCCSock.cpp

@@ -187,7 +187,7 @@ CFile* CDCCSock::OpenFile(bool bWrite) {
 		// The DCC specs only allow file transfers with files smaller
 		// than 4GiB (see ReadData()).
 		off_t uFileSize = m_pFile->GetSize();
-		if (uFileSize > 0xffffffff) {
+		if (uFileSize > (off_t) 0xffffffff) {
 			delete m_pFile;
 			m_pFile = NULL;
 			m_pUser->PutModule(m_sModuleName, "DCC -> [" + m_sRemoteNick + "] - File too large (>4 GiB) [" + m_sLocalFile + "]");