implement support for -finstrument-functions, patch by Nelson
Elhage!

llvm-svn: 106507
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index a925047..e7a75a6 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -840,6 +840,8 @@
   Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
   Opts.VerifyModule = !Args.hasArg(OPT_disable_llvm_verifier);
 
+  Opts.InstrumentFunctions = Args.hasArg(OPT_finstrument_functions);
+
   if (Arg *A = Args.getLastArg(OPT_fobjc_dispatch_method_EQ)) {
     llvm::StringRef Name = A->getValue(Args);
     unsigned Method = llvm::StringSwitch<unsigned>(Name)