One last portability fix attempt for r195886

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@195891 91177308-0d34-0410-b5e6-96231b3b80d8

test/Frontend/rewrite-includes-bom.c

-// RUN: grep -E "^\\xEF\\xBB\\xBF" %S/Inputs/rewrite-includes-bom.h
-// RUN: %clang_cc1 -E -frewrite-includes -I %S/Inputs %s -o - | %clang_cc1 -fsyntax-only -verify -x c - | not grep -E "\\xEF\\xBB\\xBF"
+// RUN: grep $'^\xEF\xBB\xBF' %S/Inputs/rewrite-includes-bom.h
+// RUN: %clang_cc1 -E -frewrite-includes -I %S/Inputs %s -o - | %clang_cc1 -fsyntax-only -verify -x c - | not grep $'\xEF\xBB\xBF'
 // expected-no-diagnostics
+// REQUIRES: shell
 
 #include "rewrite-includes-bom.h"