In yocto versions before dizzy/master the build was done
in the source directory and when configure was executed
twice in the same directory we would have a build failure
due the symlink already existing. Simply assume that if
the ln fails the link is already there.
Out of disk space situations are handled more early by
OE and missing files will be found by configure.
In dizzy/master OE will clean the build directory before
calling configure so the issue does not apply there.
Fixes: SYS#1170
a561f17dac