Interix build warning fix

/bin/sh ../libtool --tag=CC --mode=compile gcc -DHAVE_CONFIG_H -I.. -I/src/g
uile-1.8.6 -I.. -g -O2 -Wall -Wmissing-prototypes -Werror -MT filesys.lo -MD -
MP -MF .deps/filesys.Tpo -c -o filesys.lo /src/guile-1.8.6/libguile/filesys.c
libtool: compile: gcc -DHAVE_CONFIG_H -I.. -I/src/guile-1.8.6 -I.. -g -O2 -Wall
-Wmissing-prototypes -Werror -MT filesys.lo -MD -MP -MF .deps/filesys.Tpo -c /s
rc/guile-1.8.6/libguile/filesys.c -DPIC -o .libs/filesys.o
/src/guile-1.8.6/libguile/filesys.c: In function `scm_readdir':
/src/guile-1.8.6/libguile/filesys.c:918: warning: implicit declaration of
function `readdir_r'

Report and fix provided by Jay Krell.

* libguile/filesys.c: On Interix, define _REENTRANT in order to pick
  up readdir_r prototype.

NEWS

@@ -15,6 +15,7 @@ Changes in 1.8.8 (since 1.8.7)
 ** Fix `wrong type arg' exceptions with IPv6 addresses
 ** Fix typos in `(srfi srfi-19)'
 ** Have `(srfi srfi-35)' provide named struct vtables
+** Fix some Interix build problems
 
 
 Changes in 1.8.7 (since 1.8.6)

THANKS

@@ -65,6 +65,7 @@ For fixes or providing information which led to a fix:
        Matthias Köppe
            Matt Kraai
          Daniel Kraft
+            Jay Krell
            Jeff Long
 	  Marco Maggi
         Gregory Marton

libguile/filesys.c

@@ -23,6 +23,9 @@
 #ifdef __hpux
 #define _POSIX_C_SOURCE 199506L  /* for readdir_r */
 #endif
+#if defined(__INTERIX) && !defined(_REENTRANT)
+# define _REENTRANT   /* ask Interix for readdir_r prototype */
+#endif
 
 #ifdef HAVE_CONFIG_H
 #  include <config.h>