The code pattern "imm0_255_neg" is used for checking if an immediate value is...

The code pattern "imm0_255_neg" is used for checking if an immediate value is a small negative number.
This patch changes the definition of negative from -0..-255 to -1..-255. I am changing this because of
a bug that we had in some of the patterns that assumed that "subs" of zero does not set the carry flag.

rdar://12028498

llvm-svn: 167963