Add plain glibc 2.12.2 + TLS/thread-safety patch dynamic loader

The following contains plain glibc 2.12.2 with TLS/thread-safety patch
on top. All the changes are contained within the dynamic loader, thus
package only includes only ld-2.12.2.so. ABI and API is not modified.

SCRAM tool file makes GLIBC_ROOT available in developer area for wrapper
scripts.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #791 from davidlt/add-glibc-tls

Add GLIBC + TLS/thread-safety patches to CMSSW