libctf: work on platforms without O_CLOEXEC.

(Not tested on any such platforms, since I don't have access to any at
the moment.  Testing encouraged.)

libctf/
	* configure.ac: Check for O_CLOEXEC.
	* ctf-decls.h (O_CLOEXEC): Define (to 0), if need be.
	* config.h.in: Regenerate.

libctf/ChangeLog

@@ -1,3 +1,10 @@
+2019-06-04  Nick Alcock  <nick.alcock@oracle.com>
+
+	* configure.ac: Check for O_CLOEXEC.
+	* ctf-decls.h (O_CLOEXEC): Define (to 0), if need be.
+	* config.h.in: Regenerate.
+	* configure: Likewise.
+
 2019-06-04  Nick Alcock  <nick.alcock@oracle.com>
 
 	* qsort_r.c: Rename to...

libctf/config.h.in

@@ -24,6 +24,9 @@
 /* Define to 1 if you have a working `mmap' system call. */
 #undef HAVE_MMAP
 
+/* Whether the platform has a definition of O_CLOEXEC. */
+#undef HAVE_O_CLOEXEC
+
 /* Define to 1 if you have the `pread' function. */
 #undef HAVE_PREAD
 

libctf/configure

@@ -6462,6 +6462,43 @@ else
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for O_CLOEXEC" >&5
+$as_echo_n "checking for O_CLOEXEC... " >&6; }
+if ${ac_cv_libctf_macro_O_CLOEXEC+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <fcntl.h>
+                       #ifndef O_CLOEXEC
+                         choke me;
+                       #endif
+
+int
+main ()
+{
+return O_CLOEXEC;
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_libctf_macro_O_CLOEXEC=yes
+else
+  ac_cv_libctf_macro_O_CLOEXEC=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_libctf_macro_O_CLOEXEC" >&5
+$as_echo "$ac_cv_libctf_macro_O_CLOEXEC" >&6; }
+
+if test $ac_cv_libctf_macro_O_CLOEXEC = yes; then
+
+$as_echo "#define HAVE_O_CLOEXEC 1" >>confdefs.h
+
+fi
+
 ac_config_files="$ac_config_files Makefile"
 
 ac_config_headers="$ac_config_headers config.h"

libctf/configure.ac

@@ -133,6 +133,22 @@ esac
 
 AM_CONDITIONAL(NEED_CTF_QSORT_R, test "${ac_cv_libctf_qsort_r_signature}" = unknown)
 
+AC_CACHE_CHECK([for O_CLOEXEC], [ac_cv_libctf_macro_O_CLOEXEC],
+  [AC_LINK_IFELSE(
+    [AC_LANG_PROGRAM([[#include <fcntl.h>
+                       #ifndef O_CLOEXEC
+                         choke me;
+                       #endif
+                     ]],
+                     [[return O_CLOEXEC;]])],
+    [ac_cv_libctf_macro_O_CLOEXEC=yes],
+    [ac_cv_libctf_macro_O_CLOEXEC=no])])
+
+if test $ac_cv_libctf_macro_O_CLOEXEC = yes; then
+  AC_DEFINE([HAVE_O_CLOEXEC], 1,
+	    [Whether the platform has a definition of O_CLOEXEC.])
+fi
+
 AC_CONFIG_FILES(Makefile)
 AC_CONFIG_HEADERS(config.h)
 AC_OUTPUT

libctf/ctf-decls.h

@@ -62,6 +62,10 @@ void ctf_qsort_r (void *base, size_t nmemb, size_t size,
 	      void *arg);
 #endif
 
+#ifndef HAVE_O_CLOEXEC
+# define O_CLOEXEC 0
+#endif
+
 #undef MAX
 #undef MIN
 #define MAX(a, b) ((a) > (b) ? (a) : (b))