BUG: adjointRotatingWallVelocity causes sensitivities to crash. Fixes #3180

If a case contains both adjointRotatingWallVelocity and adjointWallVelocity boundary conditions and sensitivity derivatives are computed over both these kind of patches, the computation of the sensitivities will crash due to an unallocated tmp. Cases with only adjointRotatingWallVelocity or adjointWallVelocity are not problematic.

Fixed by safeguarding the usage of adjointBoundaryCondition..dxdbMult()