This patch fixes several small problems with external layouts support in MicrosoftRecordLayoutBuilder:
- aligns properly the size of a struct that ends with a bit field. It was aligned on byte before, not on the size of the field, so the struct size was smaller than it should be;
- adjusts the struct size when injecting a vbptr in the case when there were no bases or fields allocated after the vbptr. Similarly, without the adjustment the struct was smaller than it should be;
- the same fix as above for the vfptr.
All these fixes affect the non-virtual size of a struct, so they are tested through non-virtual inheritance.