Revert "Remove redundant "std::move"s in return statements"

The build failed with

  error: call to deleted constructor of 'llvm::Error'

errors.

This reverts commit 1c2241a7936bf85aa68aef94bd40c3ba77d8ddf2.
diff --git a/llvm/lib/Support/APFloat.cpp b/llvm/lib/Support/APFloat.cpp
index 6b72593..03f0bb1 100644
--- a/llvm/lib/Support/APFloat.cpp
+++ b/llvm/lib/Support/APFloat.cpp
@@ -2518,7 +2518,7 @@
   /* Scan the text.  */
   StringRef::iterator p = str.begin();
   if (Error Err = interpretDecimal(p, str.end(), &D))
-    return Err;
+    return std::move(Err);
 
   /* Handle the quick cases.  First the case of no significant digits,
      i.e. zero, and then exponents that are obviously too large or too
diff --git a/llvm/lib/Support/FileCheck.cpp b/llvm/lib/Support/FileCheck.cpp
index 5c5a510..23e1ece 100644
--- a/llvm/lib/Support/FileCheck.cpp
+++ b/llvm/lib/Support/FileCheck.cpp
@@ -86,7 +86,7 @@
       Err = joinErrors(std::move(Err), LeftOp.takeError());
     if (!RightOp)
       Err = joinErrors(std::move(Err), RightOp.takeError());
-    return Err;
+    return std::move(Err);
   }
 
   return EvalBinop(*LeftOp, *RightOp);
@@ -284,7 +284,7 @@
                     FileCheckPatternContext *Context, const SourceMgr &SM) {
   Expr = Expr.ltrim(SpaceChars);
   if (Expr.empty())
-    return LeftOp;
+    return std::move(LeftOp);
 
   // Check if this is a supported operation and select a function to perform
   // it.
@@ -425,7 +425,7 @@
     DefinedNumericVariable = *ParseResult;
   }
 
-  return ExpressionPointer;
+  return std::move(ExpressionPointer);
 }
 
 bool Pattern::parsePattern(StringRef PatternStr, StringRef Prefix,
diff --git a/llvm/lib/Support/JSON.cpp b/llvm/lib/Support/JSON.cpp
index d44eafa..16b1d11 100644
--- a/llvm/lib/Support/JSON.cpp
+++ b/llvm/lib/Support/JSON.cpp
@@ -513,7 +513,7 @@
   if (P.checkUTF8())
     if (P.parseValue(E))
       if (P.assertEnd())
-        return E;
+        return std::move(E);
   return P.takeError();
 }
 char ParseError::ID = 0;
diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp
index a7c7c35..e4027ca 100644
--- a/llvm/lib/Support/MemoryBuffer.cpp
+++ b/llvm/lib/Support/MemoryBuffer.cpp
@@ -128,7 +128,7 @@
   if (!Buf)
     return make_error_code(errc::not_enough_memory);
   memcpy(Buf->getBufferStart(), InputData.data(), InputData.size());
-  return Buf;
+  return std::move(Buf);
 }
 
 std::unique_ptr<MemoryBuffer>
@@ -398,7 +398,7 @@
                                                          Offset, EC));
   if (EC)
     return EC;
-  return Result;
+  return std::move(Result);
 }
 
 ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
@@ -450,7 +450,7 @@
         new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile<MB>(
             RequiresNullTerminator, FD, MapSize, Offset, EC));
     if (!EC)
-      return Result;
+      return std::move(Result);
   }
 
   auto Buf = WritableMemoryBuffer::getNewUninitMemBuffer(MapSize, Filename);
@@ -475,7 +475,7 @@
     Offset += *ReadBytes;
   }
 
-  return Buf;
+  return std::move(Buf);
 }
 
 ErrorOr<std::unique_ptr<MemoryBuffer>>
diff --git a/llvm/lib/Support/Path.cpp b/llvm/lib/Support/Path.cpp
index 85698f1..fa3bf47 100644
--- a/llvm/lib/Support/Path.cpp
+++ b/llvm/lib/Support/Path.cpp
@@ -1264,7 +1264,7 @@
     return errorCodeToError(EC);
   }
 #endif
-  return Ret;
+  return std::move(Ret);
 }
 }
 
diff --git a/llvm/lib/Support/YAMLTraits.cpp b/llvm/lib/Support/YAMLTraits.cpp
index de7da63..5f0cedc 100644
--- a/llvm/lib/Support/YAMLTraits.cpp
+++ b/llvm/lib/Support/YAMLTraits.cpp
@@ -388,7 +388,7 @@
         break;
       SQHNode->Entries.push_back(std::move(Entry));
     }
-    return SQHNode;
+    return std::move(SQHNode);
   } else if (MappingNode *Map = dyn_cast<MappingNode>(N)) {
     auto mapHNode = std::make_unique<MapHNode>(N);
     for (KeyValueNode &KVN : *Map) {
@@ -413,7 +413,7 @@
         break;
       mapHNode->Mapping[KeyStr] = std::move(ValueHNode);
     }
-    return mapHNode;
+    return std::move(mapHNode);
   } else if (isa<NullNode>(N)) {
     return std::make_unique<EmptyHNode>(N);
   } else {