revert r196152.
This is a duplicate implementation.
E.g. this patch defines:
     float64_t vabd_f64(float64_t a, float64_t b)
But there is already a similar intrinsic "vabdd_f64" with the same types.
Also, this intrinsic will be conflicted to the vector type intrinsic as following(Which is implemented by me and will be committed to trunk):
     float64x1_t vabd_f64(float64x1_t a, float64x1_t b).
Two functions shouldn't have a same name in arm_neon.h.
According to ARM ACLE document, such vabd_f64 with float64_t is not existing.
So I revert this commit.