support multiplication by constant negative integers

this constmul code is still buggy though, so beware. mul by 7427 is currently
broken, for example. will fix it when I get a moment :)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21652 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed