Cleanup not needed parts

- Drop hard dependency on glibc in gcc-toolfile.spec
- Remove a switch allowing to control post-install relocation.
  Everything is now done based on .interp section content.
  If ELF binary has .interp with $SCRAM_ARCH/external/glibc in
  path we then do post-install relocation on it.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>