Update configure.ac

configure.ac

-AC_PREREQ(2.68)
+AC_PREREQ([2.69])
 AC_COPYRIGHT([Copyright 2021  UPLEX - Nils Goroll Systemoptimierung])
-AC_INIT([elbestream], [trunk], [varnish-support@uplex.de], [elbestream])
+AC_INIT([elbestream],[trunk],[varnish-support@uplex.de],[elbestream])
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_SRCDIR(elbestream.c)
-AM_CONFIG_HEADER(config.h)
-AC_CANONICAL_SYSTEM
+AC_CONFIG_HEADERS(config.h)
+AC_CANONICAL_TARGET
 AC_LANG(C)
 
 AM_INIT_AUTOMAKE([1.12 -Wall -Werror foreign parallel-tests])
 AM_SILENT_RULES([yes])
 
 AC_PROG_CC
-AC_PROG_CC_STDC
 if test "x$ac_cv_prog_cc_c99" = xno; then
 	AC_MSG_ERROR([Could not find a C99 compatible compiler])
 fi