If the target says that an extending load is not legal, regardless of whether

it involves specific floating-point types, legalize should expand an
extending load to a non-extending load followed by a separate extend operation.
For example, we currently expand SEXTLOAD to EXTLOAD+SIGN_EXTEND_INREG (and
assert that EXTLOAD should always be supported).  Now we can expand that to
LOAD+SIGN_EXTEND.  This is needed to allow vector SIGN_EXTEND and ZERO_EXTEND
to be used for NEON.

llvm-svn: 111586