Revert r338354 "[ARM] Revert r337821"

Disable ARMCodeGenPrepare by default again. It is causing verifier
failues in V8 that look like:

  Duplicate integer as switch case
  switch i32 %trunc, label %if.end13 [
    i32 0, label %cleanup36
    i32 0, label %if.then8
  ], !dbg !4981
  i32 0
  fatal error: error in backend: Broken function found, compilation aborted!

I will continue reducing the test case and send it along.

llvm-svn: 338452
diff --git a/llvm/lib/Target/ARM/ARMCodeGenPrepare.cpp b/llvm/lib/Target/ARM/ARMCodeGenPrepare.cpp
index 83ba345..24071277 100644
--- a/llvm/lib/Target/ARM/ARMCodeGenPrepare.cpp
+++ b/llvm/lib/Target/ARM/ARMCodeGenPrepare.cpp
@@ -42,7 +42,7 @@
 using namespace llvm;
 
 static cl::opt<bool>
-DisableCGP("arm-disable-cgp", cl::Hidden, cl::init(false),
+DisableCGP("arm-disable-cgp", cl::Hidden, cl::init(true),
            cl::desc("Disable ARM specific CodeGenPrepare pass"));
 
 static cl::opt<bool>