[noinline attribute] add noinline attribute.

Propagate it to SILFunction and use it in PerformanceInliner. We also serialize
and parse the attribute.

rdar://15882816


Swift SVN r19150

lib/Serialization/SerializeSIL.cpp

@@ -221,6 +221,7 @@ void SILSerializer::writeSILFunction(const SILFunction &F, bool DeclOnly) {
                                 toStableSILLinkage(F.getLinkage()),
                                 (unsigned)F.isTransparent(),
                                 (unsigned)F.isGlobalInit(),
+                                (unsigned)F.isNoinline(),
                                 FnID);
 
   if (DeclOnly || F.isAvailableExternally() || F.isExternalDeclaration())