flexdll does not give the -L flag to MSVC link.exe

[jonahbeckford]

Original issue: dbuenzli/tsdl#96 (comment)

The relevant snippet:

+ flexlink -x64 -merge-manifest -stack 33554432 -g -o src\dlltsdl_stubs.dll SDL2d.lib src/tsdl_stubs.obj    -LY:/source/tsdl/_opam/share/dkcoder-c/debug/lib/pkgconfig/../../lib -LC:/Users/beckf/AppData/Local/Programs/DKMLNA~1/lib/ocaml\flexdll

+ link -lib -nologo -machine:AMD64 -out:src\libtsdl_stubs.lib  SDL2d.lib src/tsdl_stubs.obj

shows that flexlink ... -Lxyz does not get translated to link ... /LIBPATH:xyz (https://learn.microsoft.com/en-us/cpp/build/reference/libpath-additional-libpath?view=msvc-170).