Remove use of llvm::TargetOptions::NoFramePointerElim

Bug: 22210139

This flag is removed from upstream.  Removing its use will enable frame
pointer elimination by default.  After the rebase, we need to add back
the ability to disable frame pointer elimination (b/22210139).

Change-Id: I594b3e6964c3069ddbb77748d22fe879289725d0
diff --git a/slang_backend.cpp b/slang_backend.cpp
index 8f4a255..4295e9c 100644
--- a/slang_backend.cpp
+++ b/slang_backend.cpp
@@ -138,8 +138,6 @@
   // Target Machine Options
   llvm::TargetOptions Options;
 
-  Options.NoFramePointerElim = mCodeGenOpts.DisableFPElim;
-
   // Use hardware FPU.
   //
   // FIXME: Need to detect the CPU capability and decide whether to use softfp.