Use __minix to detect Minix, which works on both ACK and GCC.

include/curl/multi.h

@@ -55,7 +55,7 @@
 /* HP-UX systems version 9, 10 and 11 lack sys/select.h and so does oldish
    libc5-based Linux systems. Only include it on system that are known to
    require it! */
-#if defined(_AIX) || defined(NETWARE) || defined(__NetBSD__) || defined(_MINIX)
+#if defined(_AIX) || defined(NETWARE) || defined(__NetBSD__) || defined(__minix)
 #include <sys/select.h>
 #endif
 

lib/if2ip.c

@@ -39,7 +39,7 @@
  */
 #if !defined(WIN32) && !defined(__BEOS__) && !defined(__CYGWIN__) && \
     !defined(__riscos__) && !defined(__INTERIX) && !defined(NETWARE) && \
-    !defined(_AMIGASF) && !defined(_MINIX)
+    !defined(_AMIGASF) && !defined(__minix)
 
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>