[vector] Remove explicit std::move

Was confusing compilers. Let them figure it out themselves.

Makes NotoNastaliqu subsetting/1000 benchmark more than twice faster:

Benchmark                                                                       Time             CPU      Time Old      Time New       CPU Old       CPU New
------------------------------------------------------------------------------------------------------------------------------------------------------------
BM_subset/subset_glyphs/NotoNastaliqUrdu-Regular.ttf/1000                    -0.5064         -0.5065           111            55           110            55
BM_subset/subset_codepoints/NotoNastaliqUrdu-Regular.ttf/1000                -0.5494         -0.5493           132            59           131            59

src/hb-vector.hh

@@ -340,7 +340,7 @@ struct hb_vector_t : std::conditional<sorted, hb_vector_t<Type, false>, hb_empty
   Type pop ()
   {
     if (!length) return Null (Type);
-    Type v = std::move (arrayZ[length - 1]);
+    Type v = arrayZ[length - 1];
     arrayZ[length - 1].~Type ();
     length--;
     return v;