meson won't link libgcc and libstdc++ statically in the 32-bit mingw environtment

[crab2313]

Meson won't pass -static-libstdc++ and -static-libgcc to the linker, when building an c++ executable under 32-bit mingw32 (msys2) environments, . And the binary produced by g++ requires libgcc_c_dw2-1.dll which is different compared to x86_64-mingw32 (don't rely on any extra DLLs).