Remove redundant FunctionDecl argument from a couple functions.

This argument was added in r254554 in order to support the
pass_object_size attribute. However, in r296076, the attribute's
presence is now also represented in FunctionProtoType's
ExtParameterInfo, and thus it's unnecessary to pass along a separate
FunctionDecl.

The functions modified are:
 RequiredArgs::forPrototype{,Plus}, and
 CodeGenTypes::ConvertFunctionType.

After this, it's also (again) unnecessary to have a separate
ConvertFunctionType function ConvertType, so convert callers back to
the latter, leaving the former as an internal helper function.

llvm-svn: 352946
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index f944504..702e18d 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -326,7 +326,7 @@
 
 #ifndef NDEBUG
   const CGFunctionInfo &CallFnInfo = CGM.getTypes().arrangeCXXMethodCall(
-      CallArgs, FPT, RequiredArgs::forPrototypePlus(FPT, 1, MD), PrefixArgs);
+      CallArgs, FPT, RequiredArgs::forPrototypePlus(FPT, 1), PrefixArgs);
   assert(CallFnInfo.getRegParm() == CurFnInfo->getRegParm() &&
          CallFnInfo.isNoReturn() == CurFnInfo->isNoReturn() &&
          CallFnInfo.getCallingConvention() == CurFnInfo->getCallingConvention());