Revert "Modify FPFeatures to use delta not absolute settings"

This reverts commit 3a748cbf86cea3844fada04eeff4cc64b01f67e0.
I'm reverting this commit because I forgot to format the commit message
propertly. Sorry for the thrash.
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index abc6081..b13d0df 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -1545,8 +1545,8 @@
 void ASTStmtWriter::VisitCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
   VisitCallExpr(E);
   Record.push_back(E->getOperator());
-  Record.AddSourceRange(E->Range);
   Record.push_back(E->getFPFeatures().getAsOpaqueInt());
+  Record.AddSourceRange(E->Range);
   Code = serialization::EXPR_CXX_OPERATOR_CALL;
 }