Defines starting with `p' in src

• PEL_DATA src/i_ibm.c:1136
• PEL_MASK src/i_ibm.c:1137
• PEL_READ_ADR src/i_ibm.c:1135
• PEL_WRITE_ADR src/i_ibm.c:1134
• PLATSPEED src/p_spec.h:270
• PLATWAIT src/p_spec.h:269
• PL_DRONE src/d_net.c:45