fix: drop lto on MinGW

Author: henryiii

tools/pybind11Common.cmake

@@ -302,6 +302,11 @@ function(_pybind11_return_if_cxx_and_linker_flags_work result cxxflags linkerfla
 endfunction()
 
 function(_pybind11_generate_lto target prefer_thin_lto)
+  if(MINGW)
+    message(STATUS "${target} disabled (problems with undefined symbols for MinGW for now)")
+    return()
+  endif()
+
   if(CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
     set(cxx_append "")
     set(linker_append "")