Fix bug arising when TQPATH is not set

During rc compile, if the TQPATH bash variable is not set, there will be an error when making a symlink to the QFramework directory. Question of whose job it is to set TQPATH aside, if it is not set, the script doesn't do what it is supposed to, nor does it exit gracefully. Essentially, what happens is:

ln -s TQPATH symlink_path

turns into:

ln -s symlink_path

so the link name becomes the target, and the symlink is produced in the working directory. The consequence of this is an annoying error which seems to be isolated but sometimes demands a fix (deleting the symlink) when rc compile is run. Here's the output of the error that in my experience only sometimes halts the rc compile process:

ln: creating symbolic link `./base': File exists
RootCore: Error failed to execute

This MR just hardcodes in the relative path to the QFramework directory if TQPath is not already defined.