include math.h when compileing

git-svn-id: svn://svn.oetiker.ch/rrdtool/branches/1.3@1888 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/program/m4/acinclude.m4 b/program/m4/acinclude.m4
index d207abbe2b35d5939d2960071e63b8156fe61e82..dff8026d066f3e42443cdab1c89b2c1f07d39321 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;