Handle the 'n' constraint

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@48091 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Basic/TargetInfo.cpp b/Basic/TargetInfo.cpp
index 8d4488a..0a561d7 100644
--- a/Basic/TargetInfo.cpp
+++ b/Basic/TargetInfo.cpp
@@ -190,6 +190,7 @@
       break;
     case 'i': // immediate integer.
     case 'I':
+    case 'n': // immediate integer with a known value.
       break;
     case 'r': // general register.
       info = (ConstraintInfo)(info|CI_AllowsRegister);