enc_neon: convert Disto4x4 to intrinsics

Change-Id: I0f00d5af2de2301e8237c2a38a9612d3645abad6
enc_mips32: disable ITransform(One) in debug builds

avoids:
src/dsp/enc_mips32.c: In function 'ITransformOne':
src/dsp/enc_mips32.c:123:3: can't find a register in class 'GR_REGS' while reloading 'asm'
src/dsp/enc_mips32.c:123:3: 'asm' operand has impossible constraints

Change-Id: Ic469667ee572f25e502c9873c913643cf7bbe89d