build: fix check for isinf/isnan

Needs to be #if not #ifdef for 'decl' checks.
Otherwise build fails on systems without these.

Signed-off-by: Steve Bennett <steveb@workware.net.au>

1 files changed, 2 insertions, 2 deletions

diff --git a/jim.c b/jim.c
index 38d8a70..68a703e 100644
--- a/jim.c
+++ b/jim.c
@@ -6176,11 +6176,11 @@ static const Jim_ObjType doubleObjType = {
     JIM_TYPE_NONE,
 };
 
-#ifndef HAVE_DECL_ISNAN
+#if !HAVE_DECL_ISNAN
 #undef isnan
 #define isnan(X) ((X) != (X))
 #endif
-#ifndef HAVE_DECL_ISINF
+#if !HAVE_DECL_ISINF
 #undef isinf
 #define isinf(X) (1.0 / (X) == 0.0)
 #endif