Move freeze() into shared/

Library code should not call freeze(), this is something that should
only be done by "application code", so moving it into shared/ is appropriate.

The fallback to call _exit() is dropped: let's trust that the infinite loop
is infinite.

src/basic/process-util.c

@@ -1037,30 +1037,6 @@ bool is_main_thread(void) {
         return cached > 0;
 }
 
-_noreturn_ void freeze(void) {
-
-        log_close();
-
-        /* Make sure nobody waits for us on a socket anymore */
-        (void) close_all_fds(NULL, 0);
-
-        sync();
-
-        /* Let's not freeze right away, but keep reaping zombies. */
-        for (;;) {
-                int r;
-                siginfo_t si = {};
-
-                r = waitid(P_ALL, 0, &si, WEXITED);
-                if (r < 0 && errno != EINTR)
-                        break;
-        }
-
-        /* waitid() failed with an unexpected error, things are really borked. Freeze now! */
-        for (;;)
-                pause();
-}
-
 unsigned long personality_from_string(const char *p) {
         int architecture;
 

src/basic/process-util.h

@@ -82,8 +82,6 @@ int pid_from_same_root_fs(pid_t pid);
 
 bool is_main_thread(void);
 
-_noreturn_ void freeze(void);
-
 #ifndef PERSONALITY_INVALID
 /* personality(7) documents that 0xffffffffUL is used for querying the
  * current personality, hence let's use that here as error