Fix NetBSD build

There was still a mistake after my earlier
a7115a47ef and
e13fc0bbdb. This finally gets it right.

configure.ac

@@ -308,7 +308,12 @@ AC_SUBST(HAVE_SECCOMP, [$have_seccomp])
 
 # Optional dependencies for better normalizing file system data
 AC_CHECK_HEADERS([sys/xattr.h])
-AC_CHECK_FUNCS([llistxattr lremovexattr])
+AS_IF([test "$ac_cv_header_sys_xattr_h" = "yes"],[
+  AC_CHECK_FUNCS([llistxattr lremovexattr])
+  AS_IF([test "$ac_cv_func_llistxattr" = "yes" && test "$ac_cv_func_lremovexattr" = "yes"],[
+    AC_DEFINE([HAVE_ACL_SUPPORT], [1], [Define if we can manipulate file system Access Control Lists])
+  ])
+])
 
 # Look for aws-cpp-sdk-s3.
 AC_LANG_PUSH(C++)

src/libstore/globals.hh

@@ -946,7 +946,9 @@ public:
           may be useful in certain scenarios (e.g. to spin up containers or
           set up userspace network interfaces in tests).
         )"};
+#endif
 
+#if HAVE_ACL_SUPPORT
     Setting<StringSet> ignoredAcls{
         this, {"security.selinux", "system.nfs4_acl", "security.csm"}, "ignored-acls",
         R"(

src/libstore/posix-fs-canonicalise.cc

@@ -1,4 +1,4 @@
-#if HAVE_SYS_XATTR_H
+#if HAVE_ACL_SUPPORT
 # include <sys/xattr.h>
 #endif
 
@@ -78,7 +78,7 @@ static void canonicalisePathMetaData_(
     if (!(S_ISREG(st.st_mode) || S_ISDIR(st.st_mode) || S_ISLNK(st.st_mode)))
         throw Error("file '%1%' has an unsupported type", path);
 
-#if HAVE_SYS_XATTR_H && HAVE_LLISTXATTR && HAVE_LREMOVEXATTR
+#if HAVE_ACL_SUPPORT
     /* Remove extended attributes / ACLs. */
     ssize_t eaSize = llistxattr(path.c_str(), nullptr, 0);