Change TableGen so that binary literals such as 0b001 are now sized.

Instead of these becoming an integer literal internally, they now become bits<n> values.

Prior to this change, 0b001 was 1 bit long.  This is confusing as clearly the user gave 3 bits.
This new type holds both the literal value and the size, and so can ensure sizes match on initializers.

For example, this used to be legal

bits<1> x = 0b00;

but now it must be written as

bits<2> x = 0b00;

llvm-svn: 215084