* src/dense/ftdense.c: Add FT_NEON flag, implement ARM NEON support
in dense_render_glyph, improve SSE performance
* src/dense/rules.mk: Replacse -msse4.1 with -march=native
* src/dense/ftdense: Use SSE4.1 for final accumulation step
(FT_SSE4_1): Macro which checks if SSE4.1 is available
* src/dense/rules.mk: Enable linking for SSE4.1