Don't take short cuts trying to avoid conditionals. This leads to
negative shift amounts and/or shifts wider than the type. VAX traps on
the former, X86 and other platforms produce incorrect results on the
latter.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@204193 91177308-0d34-0410-b5e6-96231b3b80d8