Revert "Add vector of cleanup/termination events to be executed before quit"

This reverts commit 8c14f0f30f.

This list is not reliable - there are many ways for fish to quit that does not
invoke these functions. It's also not necessary since the history is correctly
saved on exec.

src/common.cpp

@@ -78,7 +78,6 @@ static void debug_shared(const wchar_t msg_level, const wcstring &msg);
 
 const wcstring whitespace = L" \t\r\n\v";
 const char *whitespace_narrow = " \t\r\n\v";
-std::stack<std::function<void()>> before_exit;
 
 bool is_whitespace(const wchar_t input) {
     for (auto c : whitespace) {

src/common.h

@@ -21,7 +21,6 @@
 #include <memory>
 #include <mutex>
 #include <sstream>
-#include <stack>
 #include <string>
 #include <tuple>
 #include <type_traits>
@@ -424,8 +423,6 @@ void assert_is_background_thread(const char *who);
 #define ASSERT_IS_BACKGROUND_THREAD_TRAMPOLINE(x) assert_is_background_thread(x)
 #define ASSERT_IS_BACKGROUND_THREAD() ASSERT_IS_BACKGROUND_THREAD_TRAMPOLINE(__FUNCTION__)
 
-extern std::stack<std::function<void()>> before_exit;
-
 // fish_mutex is a wrapper around std::mutex that tracks whether it is locked, allowing for checking
 // if the mutex is locked. It owns a boolean guarded by the lock that records whether the lock is
 // currently locked; this is only used by assertions for correctness.

src/exec.cpp

@@ -359,12 +359,6 @@ static bool can_use_posix_spawn_for_job(const job_t *job, const process_t *proce
 void internal_exec(job_t *j, const io_chain_t &&all_ios) {
     // Do a regular launch -  but without forking first...
 
-    // since we are about to quit, make sure to run pending cleanup tasks
-    while (!before_exit.empty()) {
-        before_exit.top()();
-        before_exit.pop();
-    }
-
     // setup_child_process makes sure signals are properly set up.
 
     // PCA This is for handling exec. Passing all_ios here matches what fish 2.0.0 and 1.x did.

src/fish.cpp

@@ -466,12 +466,6 @@ int main(int argc, char **argv) {
         parser.emit_profiling(s_profiling_output_filename);
     }
 
-    // since we exit without destructors, we need some way to run cleanup code when necessary
-    while (!before_exit.empty()) {
-        before_exit.top()();
-        before_exit.pop();
-    }
-
     history_save_all();
     proc_destroy();
     exit_without_destructors(exit_status);