LLD COFF: close handles to objects used to link
LLD COFF: close handles to objects used to link

fixes test failures on windows
See #302

patch sent upstream:
http://lists.llvm.org/pipermail/llvm-dev/2017-October/118234.html

raulgrell/zig,Dimenus/zig,zig-lang/zig,raulgrell/zig,andrewrk/zig,Dimenus/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig,Dimenus/zig,raulgrell/zig,andrewrk/zig,zig-lang/zig