When linking for mingw with libtool, with lld as linker (where lld 
impersonates GNU ld and implements the subset of commonly used GNU ld 
features), libtool will use a linker script for passing long lists of 
object files to the linker.

This fails with lld, where the mingw/coff part of lld doesn't support 
linker script. It does support response files (which also GNU ld does) 
though, so by making libtool check for support for response files before 
linker script (which is assumed to be supported if with_gnu_ld is set), 
this issue can be avoided. The attached patch accomplishes this. Are there 
any drawbacks to this approach, other than being less tested than the 
current status quo?

This patch has been carried in msys2's copy of libtool since late last 
year, with no reported issues to my knowledge.

// Martin