[InstCombine] Fix a compilation bug

With gcc 6.3.0, I hit the following compilation bug.
  ../lib/Transforms/InstCombine/InstCombineVectorOps.cpp:937:2: error: extra ‘;’ [-Werror=pedantic]
   };
    ^
  cc1plus: all warnings being treated as errors

The error is introduced by Commit ae7f0881 ("[InstCombine]
Aggregate reconstruction simplification (PR47060)")