verify-uselistorder: Change the default -num-shuffles=5

Change the default for `-num-shuffles` to 5 and better document the
algorithm in the header docs of `verify-uselistorder`.

llvm-svn: 214419
diff --git a/llvm/test/Bitcode/upgrade-loop-metadata.ll b/llvm/test/Bitcode/upgrade-loop-metadata.ll
index 3c1db98..806eda6 100644
--- a/llvm/test/Bitcode/upgrade-loop-metadata.ll
+++ b/llvm/test/Bitcode/upgrade-loop-metadata.ll
@@ -1,7 +1,7 @@
 ; Test to make sure loop vectorizer metadata is automatically upgraded.
 ;
 ; RUN: llvm-dis < %s.bc | FileCheck %s
-; RUN: verify-uselistorder < %s.bc -preserve-bc-use-list-order -num-shuffles=5
+; RUN: verify-uselistorder < %s.bc -preserve-bc-use-list-order
 
 define void @_Z28loop_with_vectorize_metadatav() {
 entry: