Tests: rewrite 'opt ... %s' to 'opt ... < %s' so that opt does not emit a ModuleID

This is done to avoid odd test failures, like the one fixed in r171243.

llvm-svn: 171246
diff --git a/llvm/test/Transforms/PhaseOrdering/PR6627.ll b/llvm/test/Transforms/PhaseOrdering/PR6627.ll
index ef9947f..58b762a 100644
--- a/llvm/test/Transforms/PhaseOrdering/PR6627.ll
+++ b/llvm/test/Transforms/PhaseOrdering/PR6627.ll
@@ -1,4 +1,4 @@
-; RUN: opt -O3 -S %s | FileCheck %s
+; RUN: opt -O3 -S < %s | FileCheck %s
 ; XFAIL: *
 
 declare i32 @doo(...)