Enhance the function_ref instruction to maintain a refcount on the

SILFunction that it references.  Use this in the mandatory inlining
pass to remove deserialized transparent functions, to clean up the
-emit-sil output of the compiler (and presumably speed up compile 
time).  This implements rdar://15272652



Swift SVN r9699

lib/SIL/SILFunction.cpp

@@ -32,6 +32,8 @@ SILFunction::SILFunction(SILModule &Module, SILLinkage Linkage,
 }
 
 SILFunction::~SILFunction() {
+  assert(RefCount == 0 &&
+         "Function cannot be deleted while function_ref's still exist");
 }
 
 void SILFunction::setDeclContext(Decl *D) {