msi: Fix loading string tables for databases that use 3-byte string references and that have a non-zero codepage (i.e. != CP_ACP).

gdi32: Multi-character character constants aren't portable as their behaviour is compiler dependent according to the C standard. Found by sparse.

wined3d: Map vertex sampler numbers to the correct internal array indices for GetTexture and SetTexture.

wined3d: Map vertex sampler numbers to the correct internal array indices for GetSamplerState and SetSamplerState.