Reapply "Fix crash on inline asm with 64bit matching input in 32bit GPR"

This reapplies commit r338206 reverted by r338214 since the bug that
r338206 uncovered has been fixed in r338268.

Add support for inline assembly with matching input operand that do not
naturally go in the register class it is constrained to (eg. double in a
32-bit GPR). Note that regular input is already handled by existing
code.

llvm-svn: 338269