"frame variable" and "target variable" shouldn't allow us to get the address of bitfields.

"frame variable" and "target variable" are trying to emulate the expression parser when doing things like:

(lldb) frame variable &my_struct.my_bitfield

And since the expression parser doesn't allow this, we shouldn't allow "frame variable" or "target variable" to succeed.

<rdar://problem/27208607> 

llvm-svn: 274703