Revert rL360675 : [APFloat] APFloat::Storage::Storage - fix use after move

This was mentioned both in https://www.viva64.com/en/b/0629/ and by scan-build checks
........
There's concerns this may just introduce a use-after-free instead.....

llvm-svn: 360770
diff --git a/llvm/lib/Support/APFloat.cpp b/llvm/lib/Support/APFloat.cpp
index aea5930..208950d 100644
--- a/llvm/lib/Support/APFloat.cpp
+++ b/llvm/lib/Support/APFloat.cpp
@@ -4418,9 +4418,9 @@
     return;
   }
   if (usesLayout<DoubleAPFloat>(Semantics)) {
-    const fltSemantics IEEESemantics = F.getSemantics();
-    new (&Double) DoubleAPFloat(Semantics, APFloat(std::move(F), IEEESemantics),
-                                APFloat(semIEEEdouble));
+    new (&Double)
+        DoubleAPFloat(Semantics, APFloat(std::move(F), F.getSemantics()),
+                      APFloat(semIEEEdouble));
     return;
   }
   llvm_unreachable("Unexpected semantics");