Ignore -cl-no-signed-zeros with Clang >=3.7.
Ignore -cl-no-signed-zeros with Clang >=3.7.

surround-io/oclgrind,mpflanzer/Oclgrind,mpflanzer/Oclgrind,bitfusionio/Oclgrind,surround-io/oclgrind,bitfusionio/Oclgrind,bitfusionio/Oclgrind,mpflanzer/Oclgrind,mpflanzer/Oclgrind,surround-io/oclgrind,surround-io/oclgrind,bitfusionio/Oclgrind