Building gcc plugin for windows on linux

Try to build the following gcc plugin on linux for windows with mingw cross compiler. The plugins are from the built avr compiler also for windows. Adapted the following plugin https://github.com/jcmvbkbc/avr-flash-vtbl.

#include <gcc-plugin.h>
#include <cp/cp-tree.h>

#ifdef _WIN32
__declspec(dllexport)
#endif

int plugin_is_GPL_compatible = 1;

void fn(void *gcc_data, void *user_data)
{
    TYPE_ADDR_SPACE (TREE_TYPE (vtbl_type_node)) = 1;
    TYPE_ADDR_SPACE (TREE_TYPE (vtbl_ptr_type_node)) = 1;
}

#ifdef _WIN32
__declspec(dllexport)
#endif    

int plugin_init (struct plugin_name_args *plugin_info,
         struct plugin_gcc_version *version)
{
    register_callback("", PLUGIN_START_UNIT, fn, NULL);
    return 0;
}

Output during compile and linking:

i686-w64-mingw32-g++ -shared -I/home/andreas/omgwtfbbq/win64/bin/../lib/gcc/avr/9.2.0/plugin/include -Wl,--export-all-symbols /home/andreas/
omgwtfbbq/win64/bin/../lib/gcc/avr/9.2.0/plugin/cc1plus.exe.a avr-flash-vtbl.c -o avr-flash-vtbl.so -I./
/usr/bin/i686-w64-mingw32-ld: /tmp/cc28ZVde.o:avr-flash-vtbl.c:(.text+0x4): undefined reference to `cp_global_trees'
/usr/bin/i686-w64-mingw32-ld: /tmp/cc28ZVde.o:avr-flash-vtbl.c:(.text+0x10): undefined reference to `cp_global_trees'
/usr/bin/i686-w64-mingw32-ld: /tmp/cc28ZVde.o:avr-flash-vtbl.c:(.text+0x44): undefined reference to `register_callback'
collect2: error: ld returned 1 exit status
make: *** [Makefile:11: avr-flash-vtbl.so] Fehler 1

The compiler flags are adapted from https://gcc.gnu.org/onlinedocs/gccint/Plugins-building.html. Has anybody already faced such a issue?