Elevate .text.syscall to .privileged

It turns out adding OpenBSD msyscall() origin verification broke the
--ftrace flag. The executable needs to issue raw syscalls while it's
rewriting itself. So they need to be in the same section, and that's
just plain simpler too.

libc/runtime/exit3.S

@@ -19,7 +19,7 @@
 #include "libc/dce.h"
 #include "libc/runtime/internal.h"
 #include "libc/macros.h"
-.text.syscall
+.privileged
 .source	__FILE__
 
 /	Terminates process, ignoring destructors and atexit() handlers.