File whatsapp-purple-libcurve25519-fix-impl-decl.patch of Package purple-whatsapp

--- a/libaxolotl-cpp/libcurve25519/src/ed25519/additions/curve_sigs.c
+++ b/libaxolotl-cpp/libcurve25519/src/ed25519/additions/curve_sigs.c
@@ -1,3 +1,4 @@
+#include <stdlib.h>
 #include <string.h>
 #include "../ge.h"
 #include "curve_sigs.h"