Defines starting with `n' in machdep/i386/fp_emul

• NEGATIVE machdep/i386/fp_emul/fp_e80387.h:292
• no_change machdep/i386/fp_emul/fp_e80387.h:300
• no_op_result machdep/i386/fp_emul/fp_e80387.h:167
• null machdep/i386/fp_emul/fp_e80387.h:164
• null_op machdep/i386/fp_emul/fp_e80387.h:188