Some minor build fixes.

lx_loader.c

@@ -810,6 +810,8 @@ static __attribute__((noreturn)) void runLxModule(LxModule *lxmod, const int arg
             : "memory"
     );
 
+    (void) endLxProcess;  // make compiler happy.
+
     __builtin_unreachable();
 } // runLxModule
 

native/os2native.h

@@ -2,7 +2,7 @@
 #define _INCL_OS2NATIVE_H_
 
 #define _POSIX_C_SOURCE 199309
-#define _BSD_SOURCE
+#define _DEFAULT_SOURCE
 #define _GNU_SOURCE
 #include <stdint.h>
 #include <stdlib.h>