[smooth] Remove SSE2.

As a result of 7b308a29dd10, the regular 64-bit execution is now faster
than SSE2. The rendering speed of script fonts at 64 ppem or larger is
improved by about 3% without SSE2. See !314 for the testing results.   

* src/smooth/ftgrays.c (gray_render_conic)[FT_INT64]: Remove SSE2 code.
1 file changed