Make -disable-simplify-libcalls work with -std-compile-opts

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125824 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/opt/opt.cpp b/tools/opt/opt.cpp
index 64c08ab..0a945df 100644
--- a/tools/opt/opt.cpp
+++ b/tools/opt/opt.cpp
@@ -427,7 +427,7 @@
                              /*OptimizeSize=*/ false,
                              /*UnitAtATime=*/ true,
                              /*UnrollLoops=*/ true,
-                             /*SimplifyLibCalls=*/ true,
+                             !DisableSimplifyLibCalls,
                              /*HaveExceptions=*/ true,
                              InliningPass);
 }