configure: Fix the isinf() detection. Fixes compilation on Solaris.
diff --git a/configure b/configure
index 40365dc..2f13aa8 100755
--- a/configure
+++ b/configure
@@ -21374,7 +21374,7 @@
 int
 main ()
 {
-float f = 0.0; isinf(f)
+float f = 0.0; int i=isinf(f)
   ;
   return 0;
 }