`cifframe_type` does not support bitfields (`_C_BFLD`)

[qmfrederik]

I'm seeing libs-base hitting the NSCAssert(0, @"Unknown type in sig"); assertion in cifframe_type.

In this case, the type being parsed is b0I1b1I1b2I1b3I1b4I1b5I1b6I1b7I1b8I1b9I1, which seems to correspond to the rflags struct used by NSView.

I hit this particular use case because as part of an effort to get libs-gui and libs-back to compile on msvc, rflags was being accessed via a function call, rather than via the instance variable.

The easy workaround appears to be to msvc port to use methods to access values of that struct, rather than the entire struct. But thought it may be worth documenting this issue anyway.