Fix a typo. It's causing consumer-typeset to miscompile. Perhaps more.

llvm-svn: 48035
diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp
index d5ce503..622d0f3 100644
--- a/llvm/lib/Support/APInt.cpp
+++ b/llvm/lib/Support/APInt.cpp
@@ -1175,7 +1175,7 @@
 /// Logical right-shift this APInt by shiftAmt.
 /// @brief Logical right-shift function.
 APInt APInt::lshr(const APInt &shiftAmt) const {
-  return ashr(shiftAmt.getLimitedValue(BitWidth));
+  return lshr(shiftAmt.getLimitedValue(BitWidth));
 }
 
 /// Logical right-shift this APInt by shiftAmt.