This patch builds and passes -L arguments to the linker in case of NetBSD target. That makes possible to use LLD linker which does not have any built-in per-OS paths configuration.
To do so the patch a) constructs paths to the library directories explicitly without using = placeholder. That allows to get correct paths whether --sysroot argument passed to the driver or not; b) calls ToolChain::AddFilePathLibArgs method to build a list of -L options from the paths list.
I hope this changes fix the following bug:
https://bugs.llvm.org/show_bug.cgi?id=33155
What's the rationale for this condition? Will it work for LLVM libc++?