fix(tests): end Windows test processes through libc before DLL detach

On Windows a test that returns from main ends through exit and ExitProcess,
which kills every other thread before the prx static destructors run at
DLL_PROCESS_DETACH. Detached host threads (the driver's async log thread,
libkernel's file watch thread, ...) die holding winpthreads and queue locks,
and a destructor that then locks a mutex, waits for the dead logger or
destroys a condition variable never returns: the test prints its last line
and hangs until the CTest timeout (#6791).

Every test executable now wraps main on MinGW. After main returns the
wrapper runs the executable's own exit handlers and static destructors
(_cexit), as exit does today, flushes the streams and ends the process with
LibcTerminate_nid_no_patch, the path the guest exit already takes. That
flushes the driver log while its thread is alive and calls TerminateProcess,
so no DLL_PROCESS_DETACH work runs after the threads are gone. The libc
shutdown callbacks are not run, as on a plain return from main on Linux. A
test that does not load libc.prx returns as before.

CMakeLists.txt

@@ -6,10 +6,15 @@ endif()
 project(Relinker CXX)
 
 set(ANYPS5_TEST_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/tests")
+set(ANYPS5_WINDOWS_TEST_EXIT "${CMAKE_CURRENT_SOURCE_DIR}/cmake/WindowsTestExit.cpp")
 
 function(add_test_executable target)
     add_executable(${target} ${ARGN})
     set_target_properties(${target} PROPERTIES RUNTIME_OUTPUT_DIRECTORY "$<1:${ANYPS5_TEST_OUTPUT_DIRECTORY}>")
+    if(MINGW)
+        target_sources(${target} PRIVATE "${ANYPS5_WINDOWS_TEST_EXIT}")
+        target_link_options(${target} PRIVATE LINKER:--wrap=main)
+    endif()
 endfunction()
 
 option(BUILD_TESTING "Build and register relinker tests" OFF)

cmake/WindowsTestExit.cpp

@@ -0,0 +1,31 @@
+#include <cstdio>
+#include <cstdlib>
+#include <iostream>
+#include <process.h>
+#include <windows.h>
+
+extern "C" int __real_main(int argc, char** argv);
+
+namespace {
+
+template<typename TFunction>
+TFunction LibcFunction(const char* name) {
+    const HMODULE libc = GetModuleHandleW(L"libc.prx");
+    if (libc == nullptr) return nullptr;
+    return reinterpret_cast<TFunction>(reinterpret_cast<void*>(GetProcAddress(libc, name)));
+}
+
+}
+
+extern "C" int __wrap_main(int argc, char** argv) {
+    const int code = __real_main(argc, argv);
+    const auto terminate = LibcFunction<void (*)(int)>("LibcTerminate_nid_no_patch");
+    if (terminate == nullptr) return code;
+    _cexit();
+    std::cout.flush();
+    std::clog.flush();
+    std::cerr.flush();
+    std::fflush(nullptr);
+    terminate(code);
+    return code;
+}