void setBitFieldSize(int bits) throws ParseException {
		if (bits < 0) {
			throw new ParseException("Negative bitfield size not permitted: " + dt.getName());
		}
		bitSize = bits;
	}
Set the bitfield size for this data type
More checking could be done here if the bitfield is set on something that
isn't a bitfield, but that probably isn't necessary.

@param bits number of bits in the bitfield
@throws ParseException exception if bitfield to large for the current data type.
Ghidra/Features/Base/src/main/java/ghidra/app/util/cparser/C/Declaration.java