Use a compile and run test for lchown() to satisfy clang++.

For glibc, previous reports were that some functions (such as lchown())
are present in libc, but are unimplemented.  That is, they always fail
and set errno=ENOSYS.  Unfortunately, the stub test doesn't work under
clang++.  Thus use a compile and run test.  This should be more reliable.

diff --git a/Configure b/Configure
index 65e624b..f01786e 100755 (executable)
--- a/Configure
+++ b/Configure
@@ -15905,27 +15905,24 @@ esac
 
 : see if lchown exists
 echo " "
-$cat > try.c <<'EOCP'
-/* System header to define __stub macros and hopefully few prototypes,
-    which can conflict with char lchown(); below.  */
-#include <assert.h>
-/* Override any gcc2 internal prototype to avoid an error.  */
-/* We use char because int might match the return type of a gcc2
-   builtin and then its argument prototype would still apply.  */
-char lchown();
-int main() {
-    /*  The GNU C library defines this for functions which it implements
-        to always fail with ENOSYS.  Some functions are actually named
-       something starting with __ and the normal name is an alias.  */
-#if defined (__stub_lchown) || defined (__stub___lchown)
-choke me
-#else
-lchown();
+$cat > try.c <<EOCP
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#$i_unistd     I_UNISTD
+#ifdef I_UNISTD
+#  include <unistd.h>
 #endif
-; return 0; }
+int main(int argc, char *argv[])
+{
+   if (lchown("./try.c", -1, getgid()) == -1) {
+       exit(EXIT_FAILURE);
+   }
+   exit(EXIT_SUCCESS);
+}
 EOCP
 set try
-if eval $compile; then
+if eval $compile && ./try; then
     $echo "lchown() found." >&4
     val="$define"
 else