Backport r71704 (add configure check for C99 round function) to trunk.
diff --git a/configure b/configure
index 17b932d..bf46b24 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
#! /bin/sh
-# From configure.in Revision: 70903 .
+# From configure.in Revision: 71009 .
# Guess values for system-dependent variables and create Makefiles.
# Generated by GNU Autoconf 2.61 for python 2.7.
#
@@ -22169,7 +22169,8 @@
-for ac_func in acosh asinh atanh copysign expm1 finite hypot log1p
+
+for ac_func in acosh asinh atanh copysign expm1 finite hypot log1p round
do
as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
{ echo "$as_me:$LINENO: checking for $ac_func" >&5