--with-libacl does not work

Commit 41c0afd7f78232fdcc0899584111c9a7540100a4 "Improve readability." changes functionality so that now all three headers <acl.h>, <sys/acl.h> and <acl/libacl.h> are required. Previously, one was sufficient.

Recent linux systems (Fedora 25, CentOS 7) do not have <acl.h> so that ./configure fails when '--with-libacl' is given.

For reference, AC_CHECK_HEADERS behavior is defined as

??
– Macro: AC_CHECK_HEADERS (HEADER-FILE..., [ACTION-IF-FOUND],
[ACTION-IF-NOT-FOUND], [INCLUDES])
...
If ACTION-IF-FOUND is given, it is additional shell code to execute when one of the
header files is found.
...
If ACTION-IF-NOT-FOUND is given, it is executed when one of the header files is not found
??

Commit changes

-    AC_CHECK_HEADERS([acl.h sys/acl.h acl/libacl.h], [libacl_header_found=yes])
-    if test "x$libacl_header_found" != "xyes" && test "x$with_libacl" != xcheck; then AC_MSG_ERROR(Cannot find libacl library headers); fi
+    AC_CHECK_HEADERS([acl.h sys/acl.h acl/libacl.h],
+      [libacl_header_found=yes],
+      [if test "x$with_libacl" != xcheck; then AC_MSG_ERROR(Cannot find libacl header files); fi])