COPKGManager: exit check size if package already installed

Old files will be remove during installation, so it should
be enough size.


Origin commit data
------------------
Commit: 337cc097c8
Author: Thilo Graf <dbt@novatux.de>
Date: 2015-02-08 (Sun, 08 Feb 2015)

src/gui/opkg_manager.cpp

@@ -224,6 +224,10 @@ bool COPKGManager::checkSize(const string& pkg_name)
 	string pkg_file = pkg_name;
 	string plain_pkg = getBaseName(pkg_file);
 
+	//exit check size if package already installed, because of auto remove of old stuff during installation
+	if (isInstalled(plain_pkg))
+		return true;
+
 	//get available root fs size
 	//TODO: Check writability!
 	struct statfs root_fs;