Remove extraneous extern keywords
Remove extraneous extern keywords

These don't really do anything in this context.

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