Define non-intrinsic instructions for vector min, max, sqrt, rsqrt, and rcp,

in addition to the intrinsic forms. Add spill-folding entries for these new
instructions, and for the scalar min and max instrinsic instructions which
were missing. And add some preliminary ISelLowering code for using the new
non-intrinsic vector sqrt instruction, and fneg and fabs.

llvm-svn: 38478