Maiko code changes needed to compile on Alpine Linux with clang. (#456)

* Changes needed to compile maiko on Alpine Linux with clang.  Switching to Alpine on github actions to streamline maiko release builds

* Changes needed to compile maiko on Alpine Linux with clang.

Switching to Alpine on github actions to streamline maiko release builds.

  * ether_nethub.c missing a couple of includes, and incorrectly including
    <sys/poll.h> instead of plain <poll.h>
  * <dirent.h> does not define MAXNAMLEN on Alpine Linux, but "locfile.h"
    compensates for this already, if it is modified to include <limits.h>,
    so use this in "dirdefs.h".

---------

Co-authored-by: Nick Briggs <nicholas.h.briggs@gmail.com>

inc/dirdefs.h

@@ -1,8 +1,9 @@
 #ifndef DIRDEFS_H
 #define DIRDEFS_H 1
-#include <dirent.h>         // for MAXNAMLEN
+
 #include <sys/types.h>      // for u_short, ino_t
 #include "lispemul.h"       // for LispPTR
+#include "locfile.h"        // for MAXNAMLEN
 /*
  * FINFO and FPROP are used to store the information of the enumerated files
  * and directories.  They are arranged in a form of linked list.  Each list is

inc/locfile.h

@@ -9,6 +9,7 @@
 /*									*/
 /************************************************************************/
 #include <errno.h>
+#include <limits.h>   /* for NAME_MAX */
 #include "lispemul.h" /* for DLword */
 
 #define	FDEV_PAGE_SIZE		512	/* 1 page == 512 byte */

src/ether_nethub.c

@@ -14,8 +14,10 @@
 #include <string.h>
 #include <unistd.h>
 #include <sys/socket.h>
+#include <sys/select.h>
+#include <sys/types.h>
 #include <arpa/inet.h>
-#include <sys/poll.h>
+#include <poll.h>
 #include <signal.h>
 #include <fcntl.h>
 #include <errno.h>