configure: replace deprecated AM_CONFIG_HEADER with AC_CONFIG_HEADERS

AM_CONFIG_HEADER has been removed in the just-released automake 1.13:
https://lists.gnu.org/archive/html/automake/2012-12/msg00038.html

diff --git a/configure.ac b/configure.ac
index 89812ba..4ebebd1 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -10,7 +10,7 @@ AM_INIT_AUTOMAKE(1.6)
 ORC_MAJORMINOR=0.4
 AC_SUBST(ORC_MAJORMINOR)
 
-AM_CONFIG_HEADER(config.h)
+AC_CONFIG_HEADER(config.h)
 
 dnl CURRENT, REVISION, AGE
 dnl - library source changed -> increment REVISION