INSTALL: add --enable-extras

INSTALL

@@ -31,6 +31,9 @@ All options:
   --with-selinux
       Link against SELInux libraries to set the expected context
       for created files.
+  --enable-extras
+      Build extras with larger external dependencies like glib,
+      libacl, libusb, ...
 
 The options used in a RPM spec file usually look like:
   --prefix=%{_prefix}
@@ -38,6 +41,7 @@ The options used in a RPM spec file usually look like:
   --sysconfdir=%{_sysconfdir}
   --with-libdir-name=%{_lib}
   --with-selinux
+  --enable-extras
 
 The defined location for scripts and binaries which are called
 from rules is /lib/udev/ on all systems and architectures. Any

configure.ac

@@ -65,6 +65,9 @@ if test "x$enable_extras" = xyes; then
 	PKG_CHECK_MODULES([GLIB], [glib-2.0 >= 2.7.0 gobject-2.0 >= 2.7.0])
 	AC_SUBST([GLIB_CFLAGS])
 	AC_SUBST([GLIB_LIBS])
+
+	AC_CHECK_LIB([acl], [acl_init], [:], AC_MSG_ERROR([libacl not found]))
+	AC_CHECK_HEADER([acl/libacl.h], [:], AC_MSG_ERROR([libacl header not found]))
 fi
 AM_CONDITIONAL([ENABLE_EXTRAS], [test "x$enable_extras" = xyes])