[Bitstream] Remove pessimizing move

Commit 4a794d8 caused build failure with -Werror -Wpessimizing-move on the clang-ppc64-aix buildbot. This patch applies Clang's suggestion to remove `std::move`.

Author: jansvoboda11

llvm/lib/Bitstream/Reader/BitstreamReader.cpp

@@ -220,9 +220,9 @@ Expected<unsigned> BitstreamCursor::readRecord(unsigned AbbrevID,
     uint32_t Code = MaybeCode.get();
     Expected<uint32_t> MaybeNumElts = ReadVBR(6);
     if (!MaybeNumElts)
-      return error(("Failed to read size: " +
-                    toString(std::move(MaybeNumElts.takeError())))
-                       .c_str());
+      return error(
+          ("Failed to read size: " + toString(MaybeNumElts.takeError()))
+              .c_str());
     uint32_t NumElts = MaybeNumElts.get();
     if (!isSizePlausible(NumElts))
       return error("Size is not plausible");
@@ -277,9 +277,9 @@ Expected<unsigned> BitstreamCursor::readRecord(unsigned AbbrevID,
       // Array case.  Read the number of elements as a vbr6.
       Expected<uint32_t> MaybeNumElts = ReadVBR(6);
       if (!MaybeNumElts)
-        return error(("Failed to read size: " +
-                      toString(std::move(MaybeNumElts.takeError())))
-                         .c_str());
+        return error(
+            ("Failed to read size: " + toString(MaybeNumElts.takeError()))
+                .c_str());
       uint32_t NumElts = MaybeNumElts.get();
       if (!isSizePlausible(NumElts))
         return error("Size is not plausible");