default long getSignedValue(byte[] b, int size) {
		return getSignedValue(b, 0, size);
	}
Get the <b>signed</b> value from the given byte array using the specified 
integer size, returned as a long.
<p>
Values with a size less than sizeof(long) will have their sign bit
extended.

@param b array containing bytes
@param size number of bytes (1 - 8) to use from array at offset 0
@return signed value from the beginning of the specified array 
@throws IndexOutOfBoundsException if byte array size is less than specified size
Ghidra/Framework/Generic/src/main/java/ghidra/util/DataConverter.java