[SimplifyLibCalls] Update an obviously copy and pasted header comment to match this file. NFC

llvm-svn: 326475
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 7dfaac8..b238768 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -7,10 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This is a utility pass used for testing the InstructionSimplify analysis.
-// The analysis is applied to every instruction, and if it simplifies then the
-// instruction is replaced by the simplification.  If you are looking for a pass
-// that performs serious instruction folding, use the instcombine pass instead.
+// This file implements the library calls simplifier. It does not implement
+// any pass, but can't be used by other passes to do simplifications.
 //
 //===----------------------------------------------------------------------===//