Fix Interix build hang

Jay Krell writes:

"Later on I get to:
gawk -f ./guile-func-name-check /src/guile-1.8.6/libguile/regex-posix.c
(./guile-snarf-docs -DHAVE_CONFIG_H -I.. -I/src/guile-1.8.6 -I.. -g -O2 -Wall -
Wmissing-prototypes -Werror /src/guile-1.8.6/libguile/regex-posix.c | \
./guile_filter_doc_snarfage --filter-snarfage) > regex-posix.doc || { rm
regex-posix.doc; false; }
cat alist.doc arbiters.doc async.doc backtrace.doc boolean.doc chars.doc
continuations.doc debug.doc deprecation.doc deprecated.doc discouraged.doc dynl.doc
dynwind.doc environments.doc eq.doc error.doc eval.doc evalext.doc extensions.doc
feature.doc fluids.doc fports.doc futures.doc gc.doc goops.doc gsubr.doc
gc-mark.doc gc-segment.doc gc-malloc.doc gc-card.doc guardians.doc hash.doc hashtab.doc
hooks.doc i18n.doc init.doc ioext.doc keywords.doc lang.doc list.doc load.doc
macros.doc mallocs.doc modules.doc numbers.doc objects.doc objprop.doc
options.doc pairs.doc ports.doc print.doc procprop.doc procs.doc properties.doc random.doc
rdelim.doc read.doc root.doc rw.doc scmsigs.doc script.doc simpos.doc smob.doc
sort.doc srcprop.doc stackchk.doc stacks.doc stime.doc strings.doc srfi-4.doc
srfi-13.doc srfi-14.doc strorder.doc strports.doc struct.doc symbols.doc
threads.doc throw.doc values.doc variable.doc vectors.doc version.doc vports.doc
weaks.doc ramap.doc unif.doc dynl.doc filesys.doc posix.doc net_db.doc
socket.doc
regex-posix.doc | GUILE="/dev/fs/C/obj/guile/pre-inst-guile" /src/guile-1.8.6/scripts/
snarf-check-and-output-texi > guile-procedures.texi || { rm guile-procedures.texi; false; }
ERROR: In procedure fport_input_waiting:
ERROR: Invalid argument

and it hangs.

[...and then later...]

Here is a very strange but successul fix for the hang. Now guile 1.8.6 builds
all the way through for me."

* libguile/iselect.h: On Interix, restrict SELECT_SET_SIZE to 1024.

libguile/iselect.h

@@ -38,7 +38,12 @@
 #ifdef FD_SET
 
 #define SELECT_TYPE fd_set
+#if defined(__INTERIX) && FD_SETSIZE == 4096
+/* Interix defines FD_SETSIZE 4096 but select rejects that. */
+#define SELECT_SET_SIZE 1024
+#else
 #define SELECT_SET_SIZE FD_SETSIZE
+#endif
 
 #else /* no FD_SET */