libnettle: -Werror=implicit-function-declaration

packages/libnettle/configure.patch

@@ -0,0 +1,11 @@
+diff -u -r ../nettle-3.3/configure ./configure
+--- ../nettle-3.3/configure	2016-10-01 09:28:38.000000000 +0200
++++ ./configure	2017-07-07 08:35:12.539208424 +0200
+@@ -7091,6 +7091,7 @@
+   CFLAGS="$CFLAGS $CCPIC"
+   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ /* end confdefs.h.  */
++#include <stdlib.h>
+ 
+ int
+ main ()