[CFLAA] Make MSVC happy. NFC.

Apparently, MSVC complains if there's an implicit conversion from
`unsigned` to `unsigned long long`, if the `unsigned` is the result of
a bit shift.

llvm-svn: 273955
diff --git a/llvm/lib/Analysis/CFLAliasAnalysis.cpp b/llvm/lib/Analysis/CFLAliasAnalysis.cpp
index 407d8e7..e2ace96 100644
--- a/llvm/lib/Analysis/CFLAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/CFLAliasAnalysis.cpp
@@ -762,7 +762,9 @@
 static StratifiedAttrs argNumberToAttr(unsigned ArgNum) {
   if (ArgNum >= AttrMaxNumArgs)
     return AttrUnknown;
-  return StratifiedAttrs(1U << (ArgNum + AttrFirstArgIndex));
+  // N.B. MSVC complains if we use `1U` here, since StratifiedAttrs' ctor takes
+  // an unsigned long long.
+  return StratifiedAttrs(1ULL << (ArgNum + AttrFirstArgIndex));
 }
 
 static Level directionOfEdgeType(EdgeType Weight) {