Remove serial port speed restriction for macOS

* macOS 10.14 Mojave SDK supports `B57600` and `B115200` in `sys/termio.h`.
  Confirmed compilation on macOS 10.14.6 with Xcode 11.3.1 Command Line Tools.

Author: jj1bdx

Diff for: src/serial_port.c

@@ -237,12 +237,8 @@ MYFDTYPE serial_port_open (char *devicename, int baud)
 	  case 9600:	cfsetispeed (&ts, B9600);	cfsetospeed (&ts, B9600); 	break;
 	  case 19200:	cfsetispeed (&ts, B19200);	cfsetospeed (&ts, B19200); 	break;
 	  case 38400:	cfsetispeed (&ts, B38400);	cfsetospeed (&ts, B38400); 	break;
-#ifndef __APPLE__
-	  // Not defined for Mac OSX.
-	  // https://groups.yahoo.com/neo/groups/direwolf_packet/conversations/messages/2072
 	  case 57600:	cfsetispeed (&ts, B57600);	cfsetospeed (&ts, B57600); 	break;
 	  case 115200:	cfsetispeed (&ts, B115200);	cfsetospeed (&ts, B115200); 	break;
-#endif
 	  default:	text_color_set(DW_COLOR_ERROR);
 	  		dw_printf ("serial_port_open: Unsupported speed %d.  Using 4800.\n", baud);
 			cfsetispeed (&ts, B4800);	cfsetospeed (&ts, B4800);