Cryptopp core2duo, 1st-gen i5/7 fix

This fix is necessary in order to use cryptopp for development. Mountain Lion and Mavericks both require, at minimum, a CPU which supports SSSE3. However the most recent version of xcode/clang will (default) compile binaries with AVX instructions (if host CPU supports them). Thus, compiling cryptopp on a 3rd-gen i7 will produce a binary which will not execute on 1st-gen Core 2 Duo and i5/i7 processors.