--- configure.in.orig
+++ configure.in
@@ -181,7 +181,7 @@ dnl Do the various CC checks *before* pr
 dnl may need to use compiler characteristics to make decisions. This macro
 dnl can only be used once within a configure script, so this prevents a
 dnl preload section from invoking the macro to get compiler info.
-AC_PROG_CC
+AC_PROG_CC_STDC
 
 dnl AC_PROG_SED is only avaliable in recent autoconf versions.
 dnl Use AC_CHECK_PROG instead if AC_PROG_SED is not present.
@@ -211,14 +211,7 @@ AC_CHECK_PROG(ASCPP, cpp, cpp)
 AC_CHECK_TOOL(AR, ar, ar)
 
 dnl Various OS checks that apparently set required flags
-ifdef([AC_USE_SYSTEM_EXTENSIONS], [
 AC_USE_SYSTEM_EXTENSIONS
-], [
-AC_AIX
-AC_MINIX
-])
-
-AC_ISC_POSIX
 APR_EBCDIC
 
 dnl this is our library name
@@ -664,15 +657,7 @@ case $host in
         fi
         ;;
     *linux*)
-        os_major=[`uname -r | sed -e 's/\([1-9][0-9]*\)\..*/\1/'`]
-        os_minor=[`uname -r | sed -e 's/[1-9][0-9]*\.\([0-9]\+\)\..*/\1/'`]
-        if test $os_major -lt 2 -o \( $os_major -eq 2 -a $os_minor -lt 4 \); then
-            AC_MSG_WARN([Configured for pre-2.4 Linux $os_major.$os_minor])
-            os_pre24linux=1
-        else
             os_pre24linux=0
-            AC_MSG_NOTICE([Configured for Linux $os_major.$os_minor])
-        fi
         ;;
     *os390)
         os_version=`uname -r | sed -e 's/\.//g'`
@@ -2060,6 +2045,8 @@ fi
 
 AC_SUBST(have_proc_invoked)
 
+AC_C_VARARRAYS
+
 AC_MSG_CHECKING(for Variable Length Arrays)
 APR_TRY_COMPILE_NO_WARNING([],
 [
@@ -2226,6 +2213,9 @@ APR_IFALLYES(header:OS.h func:create_sem
 if test "x$apr_lock_method" != "x"; then
     APR_DECISION_FORCE($apr_lock_method)
 fi
+
+APR_DECIDE(USE_PROC_PTHREAD_SERIALIZE, [cross-process pthread mutexes])
+
 APR_END_DECISION
 AC_DEFINE_UNQUOTED($ac_decision)
 
--- poll/unix/poll.c.orig
+++ poll/unix/poll.c
@@ -73,7 +73,7 @@ APR_DECLARE(apr_status_t) apr_poll(apr_p
                                    apr_interval_time_t timeout)
 {
     int i, num_to_poll;
-#ifdef HAVE_VLA
+#ifdef HAVE_C_VARARRAYS
     /* XXX: I trust that this is a segv when insufficient stack exists? */
     struct pollfd pollset[num];
 #elif defined(HAVE_ALLOCA)
@@ -129,7 +129,7 @@ APR_DECLARE(apr_status_t) apr_poll(apr_p
         }
     }
     
-#if !defined(HAVE_VLA) && !defined(HAVE_ALLOCA)
+#if !defined(HAVE_C_VARARRAYS) && !defined(HAVE_ALLOCA)
     if (num > SMALL_POLLSET_LIMIT) {
         free(pollset);
     }