include math.h when testing IEEE

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk@1887 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/program/m4/acinclude.m4 b/program/m4/acinclude.m4
index f1b611920503072d8556b39d33ea28c9a745a9aa..c1e5c4bd9d3adea7155dfc3b5e964c06842a103d 100644 (file)
--- a/program/m4/acinclude.m4
+++ b/program/m4/acinclude.m4
@@ -390,6 +390,10 @@ AC_CACHE_VAL([rd_cv_ieee_$2],
 #  define isinf(a) (fpclassify(a) == FP_INFINITE)
 #endif
 
+#if HAVE_MATH_H
+#include <math.h>
+#endif
+
 #include <stdio.h>
 int main(void){
     double rrdnan,rrdinf,rrdc,rrdzero;