Check for possibly undefined SIPHASH_MAIN using #ifdef

"#if SIPHASH_MAIN" results in -Wundef warning with recent gcc/clang and
this change suppresses it.

diff --git a/expat/lib/siphash.h b/expat/lib/siphash.h
index 30a6f11d93cb230d86cf1351c39093c88df9ff8c..d40ae7ff1b6dd621ba4d5345efdc8ec388add1f5 100644 (file)
--- a/expat/lib/siphash.h
+++ b/expat/lib/siphash.h
@@ -350,7 +350,7 @@ static int sip24_valid(void) {
 } /* sip24_valid() */
 
 
-#if SIPHASH_MAIN
+#ifdef SIPHASH_MAIN
 
 #include <stdio.h>