feat(libc): implement shared legacy sigvec support

core/libs/tests/SigvecModulesExceptions.cpp

@@ -0,0 +1,27 @@
+#include "prx/libc/include/LegacySignals.hpp"
+#include <array>
+#include <cstring>
+#include <stdexcept>
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+extern "C" bool SigvecMissingBackend_nid_no_patch(decltype(&sigvec_nid_postfix) first,
+    decltype(&sigvec_nid_postfix) second, const void* core) {
+#ifdef _WIN32
+    const auto libc = GetModuleHandleW(L"libc.prx");
+    if (libc == nullptr || reinterpret_cast<const void*>(GetProcAddress(libc, "LegacySigvec_nid_no_patch")) != core) return false;
+#else
+    if (reinterpret_cast<const void*>(&LegacySigvec_nid_no_patch) != core) return false;
+#endif
+    for (const auto function : std::array{first, second}) {
+        bool threw = false;
+        try {
+            function(30, nullptr, nullptr);
+        } catch (const std::runtime_error& error) {
+            threw = std::strcmp(error.what(), "sigvec: libkernel has not registered sigaction") == 0;
+        }
+        if (!threw) return false;
+    }
+    return true;
+}