assorted fixes:

  * clean up immediates (we use 14, 22 and 64 bit immediates now. sane.)
  * fold r0/f0/f1 registers into comparisons against 0/0.0/1.0
  * fix nasty thinko - didn't use two-address form of conditional add
    for extending bools to integers, so occasionally there would be
    garbage in the result. it's amazing how often zeros are just
    sitting around in registers ;) - this should fix a bunch of tests.

llvm-svn: 21221