if __NR_msync does not exist, dont try and create a syscall for it

libc/sysdeps/linux/common/msync.c

@@ -9,9 +9,14 @@
 
 #include "syscalls.h"
 #include <unistd.h>
+
+#ifdef __NR_msync
+
 #include <sys/mman.h>
 
 extern __typeof(msync) __libc_msync;
 #define __NR___libc_msync __NR_msync
 _syscall3(int, __libc_msync, void *, addr, size_t, length, int, flags);
 weak_alias(__libc_msync,msync)
+
+#endif