Improve NEON32 encoding speed
Improve NEON32 encoding speed

The enc_translate function now uses the same tricks as the SSSE3 one.

Speed-up on iPhone SE using Apple LLVM version 8.0.0 (clang-800.0.38)
NEON32: +33% compared to previous version

htot/base64,aklomp/base64,aklomp/base64,aklomp/base64,htot/base64,htot/base64