Dodo Nethub support (#445)

* added support for XNS networking via Dodo-Nethub

* NetHub connection now optional (only if -nh-host is given); released NetHub-related changes to 'ether.c' to the public domain

* Added file using-dodo-networking-with-maiko.md

Documentation for building and using the Dodo-networking addition to Maiko

* Added support for running Maiko unter cygwin/x86_64-x

* Migrate Addr68k/NativeAlignment{2,4} in Nethub code, move timer/async defines to platform.h

* added missing include <netinet/in.h> for FreeBSD

* updated 'compile-flags' with added flags

* splitted ether.c in 3 (_common, _sunos, _nethub)

* reworks/modifications for nbriggs' pull-request review comments

* addintional additions for nbriggs' pull-request review comments

* get the Lisp packet lengths with 'LispInt2CInt'

* renamed variables in dblwordsSwap to indicate it's about double-words

* fixed wrong preprocessor directive unnoticed by clang

* added networking choice option to cmake build, fix to printf warning

- for cmake specify the networking to use with -DMAIKO_NETWORK_TYPE=<type>
- with <type> one of: NONE, SUN_DLPI, SUN_NIT, NETHUB
- e.g.: cmake .. -DMAIKO_NETWORK_TYPE=NETHUB

* integrated improvement to sendPacket() proposed by nbriggs

* integrated fix for SIGBUS on 32-bit big-endian, provided by nbriggs

* MAIKO_ENABLE_ETHERNET should not be unconditionally set on Solaris systems

* Receiving an ethernet packet is an ether interrupt but not an i/o interrupt.

Co-authored-by: dev hawala <devhawala@x.y>
Co-authored-by: Nick Briggs <nicholas.h.briggs@gmail.com>

src/keyevent.c

@@ -61,9 +61,9 @@ void Mouse_hndlr(void); /* Fields mouse events from driver        */
 #include "osmsgdefs.h"
 #include "xwinmandefs.h"
 
-#ifdef MAIKO_ENABLE_ETHERNET
+#if defined(MAIKO_ENABLE_ETHERNET) || defined(MAIKO_ENABLE_NETHUB)
 #include "etherdefs.h"
-#endif /* MAIKO_ENABLE_ETHERNET */
+#endif /* MAIKO_ENABLE_ETHERNET or MAIKO_ENABLE_NETHUB */
 
 #include "dbprint.h"
 #if (defined(DOS) || defined(XWINDOW))
@@ -124,9 +124,9 @@ extern volatile sig_atomic_t XNeedSignal;
 
 extern int LogFileFd;
 
-#ifdef MAIKO_ENABLE_ETHERNET
+#if defined(MAIKO_ENABLE_ETHERNET) || defined(MAIKO_ENABLE_NETHUB)
 extern int ether_fd;
-#endif /* MAIKO_ENABLE_ETHERNET */
+#endif /* MAIKO_ENABLE_ETHERNET or MAIKO_ENABLE_NETHUB */
 
 extern DLword *DisplayRegion68k;
 
@@ -263,6 +263,10 @@ void process_io_events()
     }
 #endif /* MAIKO_ENABLE_ETHERNET */
 
+#ifdef MAIKO_ENABLE_NETHUB
+    check_ether();
+#endif /* MAIKO_ENABLE_NETHUB */
+
 #ifdef RS232
     if (RS232C_Fd >= 0 && (FD_ISSET(RS232C_Fd, &rfds) || (RS232C_remain_data && rs232c_lisp_is_ready())))
       rs232c_read();