Let configure detect availability of libacl and of Linux listxattr call

and aaip-os work around eventual missing functionality

configure.ac

@@ -146,6 +146,37 @@ AC_ARG_ENABLE(verbose-debug,
 	AC_DEFINE(LIBISOFS_VERBOSE_DEBUG, 1))
 
 
+dnl ts A90123
+AC_ARG_ENABLE(libacl,
+[  --enable-libacl    Enable use of libacl by libisofs, default=yes],
+               , enable_libacl=yes)
+if test x$enable_libacl = xyes; then
+dnl Check whether there is libacl-devel and libacl-runtime.
+dnl If not, erase this macro which would enable use of acl_to_text and others
+    LIBACL_DEF="-DLibisofs_with_aaip_acL"
+dnl The empty yes case obviously causes -lacl to be linked
+    AC_CHECK_HEADER(sys/acl.h, AC_CHECK_LIB(acl, acl_to_text, , LIBACL_DEF= ), LIBACL_DEF= )
+else
+    LIBACL_DEF=
+fi
+AC_SUBST(LIBACL_DEF)
+
+
+dnl ts A90123
+AC_ARG_ENABLE(xattr,
+[  --enable-xattr     Enable use of xattr by libisofs, default=yes],
+               , enable_xattr=yes)
+if test x$enable_xattr = xyes; then
+dnl Check whether there is the header for Linux xattr. 
+dnl If not, erase this macro which would enable use of listxattr and others
+    XATTR_DEF="-DLibisofs_with_aaip_xattR"
+    AC_CHECK_HEADER(attr/xattr.h, AC_CHECK_LIB(c, listxattr, X= , XATTR_DEF= ), XATTR_DEF= )
+else
+    XATTR_DEF=
+fi
+AC_SUBST(XATTR_DEF)
+
+
 AC_CONFIG_FILES([
 	Makefile
 	doc/doxygen.conf