strongswan: Include musl.h after _GNU_SOURCE define

musl.h was included before _GNU_SOURCE in 101-musl-fixes patch
leading to compilation issue on gcc (RTLD_DEFAULT not being
defined in dlfcn.h due to __USE_GNU not being set).
As described in the feature test macro man page feature macro
can be defined in the source code but need to be defined before
including any headers.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

net/strongswan/patches/101-musl-fixes.patch

@@ -52,15 +52,14 @@
 +#undef encrypt
 --- a/src/libcharon/plugins/kernel_netlink/kernel_netlink_ipsec.c
 +++ b/src/libcharon/plugins/kernel_netlink/kernel_netlink_ipsec.c
-@@ -18,6 +18,8 @@
-  * for more details.
+@@ -19,6 +19,7 @@
   */
  
-+#include <musl.h>
-+
  #define _GNU_SOURCE
++#include <musl.h>
  #include <sys/types.h>
  #include <sys/socket.h>
+ #include <stdint.h>
 --- a/src/libcharon/plugins/kernel_netlink/kernel_netlink_net.c
 +++ b/src/libcharon/plugins/kernel_netlink/kernel_netlink_net.c
 @@ -37,6 +37,8 @@