Fix comment about Intr*Mem properties

Summary:
Follow up to D19291: it now makes sense to use two Intr*Mem properties,
in particular IntrReadMem + IntrArgMemOnly is common.

Pointed out by Mikael Holmén.

Reviewers: uabelho, joker.eph, reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D19418

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267238 91177308-0d34-0410-b5e6-96231b3b80d8

Author: nhaehnle

include/llvm/IR/Intrinsics.td

@@ -19,9 +19,7 @@ include "llvm/CodeGen/ValueTypes.td"
 
 class IntrinsicProperty;
 
-// Intr*Mem - Memory properties.  An intrinsic is allowed to have at most one of
-// these properties set.  They are listed from the most aggressive (best to use
-// if correct) to the least aggressive.  If no property is set, the worst case
+// Intr*Mem - Memory properties.  If no property is set, the worst case
 // is assumed (it may read and write any memory it can get access to and it may
 // have other side effects).