COMP: Do not use -fno-ipa-cp-clone with clang.

The flag is only known to have issues with GCC 4.8.2.  Disable for clang to
avoid the warning:

  clang: warning: argument unused during compilation: '-fno-ipa-cp-clone'

Change-Id: If81b65d315b43d342ffa430fa17a202f19305b7c
ENH: Bump ITK version to 4.5.1.

Change-Id: Id795e74bd0d861f69698a8c1b04a0f99d9a74e54