fts: Fix compilation error with MSVC 14

[Bruno Haible]

A testdir fails to compile on MSVC 14, because of this error:

source='../../gllib/fts.c' object='fts.obj' libtool=no \
DEPDIR=.deps depmode=msvc7 /bin/sh ../../build-aux/depcomp \
/home/bruno/msvc/compile cl -nologo -DHAVE_CONFIG_H -DEXEEXT=\".exe\" 
-DEXEEXT=\".exe\" -DNO_XMALLOC -DEXEEXT=\".exe\" -I. -I../../gllib -I..  
-DGNULIB_STRICT_CHECKING=1 -D_WIN32_WINNT=_WIN32_WINNT_WIN7 
-I/usr/local/msvc64/include  -MD -c -o fts.obj `cygpath -w '../../gllib/fts.c'`
fts.c
c:\cygwin64\home\bruno\testdir-all\gllib\i-ring.h(21): warning C4116: unnamed 
type definition in parentheses
C:\cygwin64\home\bruno\testdir-all\gllib\fts.c(1205): error C2065: 'S_IFBLK': 
undeclared identifier
...
make[4]: *** [Makefile:10692: fts.obj] Error 2

This patch fixes it.


2022-09-04  Bruno Haible  <bruno@clisp.org>

        fts: Fix compilation error with MSVC 14.
        * lib/fts.c (S_IFBLK): Add fallback definition.

diff --git a/lib/fts.c b/lib/fts.c
index 494a63af96..a7b5b77d79 100644
--- a/lib/fts.c
+++ b/lib/fts.c
@@ -115,6 +115,9 @@ static char sccsid[] = "@(#)fts.c       8.6 (Berkeley) 
8/14/94";
 # define DT_SOCK 7
 #endif
 
+#ifndef S_IFBLK
+# define S_IFBLK 0
+#endif
 #ifndef S_IFLNK
 # define S_IFLNK 0
 #endif