[Cooker] small glibc install error

[David Walser]

When installing during the installation, glibc's %post fails, because 
coreutils (owner of rm) isn't installed yet, and the post script tries 
to run rm.  The file it's rm'ing as far as I can tell, only exists when 
upgrading the glibc RPM, so it's not critical, but it's still an error.

Possible solutions:
1) glibc have a PreReq on coreutils
2) move that rm command inside the if [ "$1" -ge 1 ] block, as it 
appears that's the only time it's relevant.