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

• ucom_op machdep/i386/fp_emul/fp_e80387.h:223
• ucom_pop machdep/i386/fp_emul/fp_e80387.h:228
• underflow_mask machdep/i386/fp_emul/fp_e80387.h:311
• unsupp machdep/i386/fp_emul/fp_e80387.h:241
• use_up machdep/i386/fp_emul/fp_e80387.h:154