build: avoid building stdbuf on cygwin

* configure.ac: Don't add stdbuf to the list of programs to build
if EXEEXT is set, as that is not handled in configure.ac for
libstdbuf.so yet (see bin_PRGRAMS handling in configure.ac).
Also the LD_PRELOAD mechanism will need to be adjusted to support
cygwin in any case, so avoid stdbuf completely in this case for now.
Problem reported by Eric Blake.

diff --git a/configure.ac b/configure.ac
index ae78cb1877477635829a0f29f52539c1150a52b9..e061a0ad5a8fcdf4e0671697b6c67627e21f16c9 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -473,7 +473,7 @@ AC_COMPILE_IFELSE(
   [stdbuf_supported=yes],
   [stdbuf_supported=no])
 AC_MSG_RESULT([$stdbuf_supported])
-if test "$stdbuf_supported" = "yes"; then
+if test "$stdbuf_supported" = "yes" && test -z "$EXEEXT"; then
   gl_ADD_PROG([optional_bin_progs], [stdbuf])
 fi