Making the code (hopefully) usable in 21.0.X again (AtlasCMake-00-01-70-01)

	* Disabled -Wl,--no-undefined for 21.0.X in this branch tag.
	* Tagging as AtlasCMake-00-01-70-01

2016-08-23 Attila Krasznahorkay <Attila.Krasznahorkay@cern.ch>
	* Fixing the issue described in ATLINFR-1240 with the setup
	  of the CALIBPATH environment variable in ZSH. As it turns out,
	  the cause of this was something that I'd label as a ZSH bug.
	* Tagging as AtlasCMake-00-01-70

2016-08-19 Attila Krasznahorkay <Attila.Krasznahorkay@cern.ch>
	* Re-enabling the -Wl,--no-undefined flag, to be used in
	  the CMAKE nightly.
	* Tagging as AtlasCMake-00-01-69


Former-commit-id: cd324943283df7dd2f64f4f6a67404be3e8c70e4