Add new function attribute - noredzone. 
Update code generator to use this attribute and remove DisableRedZone target option.
Update llc to set this attribute when -disable-red-zone command line option is used.

llvm-svn: 72894
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 8db4c71..4f8be88 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -730,7 +730,7 @@
     case lltok::kw_optsize:      Attrs |= Attribute::OptimizeForSize; break;
     case lltok::kw_ssp:          Attrs |= Attribute::StackProtect; break;
     case lltok::kw_sspreq:       Attrs |= Attribute::StackProtectReq; break;
-
+    case lltok::kw_noredzone:    Attrs |= Attribute::NoRedZone; break;
         
     case lltok::kw_align: {
       unsigned Alignment;