Bitcode: Correctly compare a Use against itself

Fix the sort of expected order in the reader to correctly return `false`
when comparing a `Use` against itself.

This was caught by test/Bitcode/binaryIntInstructions.3.2.ll, so I'm
adding a `RUN` line using `llvm-uselistorder` for every test in
`test/Bitcode` that passes.

A few tests still fail, so I'll investigate those next.

This is part of PR5680.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214157 91177308-0d34-0410-b5e6-96231b3b80d8

test/Bitcode/flags.ll

@@ -1,6 +1,7 @@
 ; RUN: llvm-as < %s | llvm-dis > %t0
 ; RUN: opt -S < %s > %t1
 ; RUN: diff %t0 %t1
+; RUN: llvm-uselistorder < %s -preserve-bc-use-list-order -num-shuffles=5
 ; PR6140
 
 ; Make sure the flags are serialized/deserialized properly for both