Fix: OS name detection error by build scripts

Fix: OS name detection error by build scripts

There is a problem detecting OS specific scripts dir if NAME variable in
/etc/os-release contains a multi-word string (e.g NAME="CentOS Linux").
To fix this we get first part of the NAME string (i.e "CentOS") for
simplicity and look for version specific scripts dir within that.

Change-Id: Ic840788875e9b486b20608a9b9e523cbd4530e31
Signed-off-by: Abdul Halim <abdul.halim@intel.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Brian Castelli <Brian.Castelli@spirent.com>