Disable linking hip_ir.ll by default

Change-Id: I4917f0d75c66eee347de41bc16d999fc563a5be2

bin/hipcc

@@ -199,7 +199,7 @@ if($HIP_PLATFORM eq "hcc"){
   }
 }
 
-if($HIP_PLATFORM eq "hcc"){
+if(($HIP_PLATFORM eq "hcc") and defined $ENV{HIP_EXPERIMENTAL}){
     $EXPORT_LL=" ";
     $ENV{HCC_EXTRA_LIBRARIES}="$HIP_PATH/lib/hip_ir.ll\n";
 }