feat: add MinGW cross-compilation support for Windows builds on Linux (#2108)

3rd/compat-mingw/dlfcn.h

@@ -0,0 +1,7 @@
+#pragma once
+
+enum { RTLD_NOW, RTLD_GLOBAL };
+
+void *dlopen(const char *path, int flag);
+const char *dlerror();
+void *dlsym(void *dl, const char *sym);