use /link before each library linker option on MSVC (#24291)

fixes #24087, refs https://forum.nim-lang.org/t/341, refs #14222, refs
#14221

The Nim compiler calls `cl` for linking as well as compilation. This
means that options to the linker have to be passed after a `/link`
argument. But the Nim compiler doesn't include this option normally,
because users may still want to pass non-linker options to `cl` at link
time.

To deal with this, a workaround is used: every single library link
option adds `/link` before it. The linker simply ignores extraneous
`/link` arguments and gives a warning instead, since it's an
unrecognized option to the linker. This is really hacky but otherwise we
need to separate linker arguments into arguments passed either to the
compiler or to the linker at link time, and this behavior wouldn't be
meaningful outside of MSVC.

I can't really test this manually but I did test that the linker ignores
`/link`. I also can't really do more than this, I don't really use MSVC
so I wouldn't know how to navigate it, or how people use it. Ideally
someone who knows more about/uses MSVC can give their input or take
over.

compiler/extccomp.nim

@@ -162,7 +162,11 @@ compiler vcc:
     linkerExe: "cl",
     linkTmpl: "$builddll$vccplatform /Fe$exefile $objfiles $buildgui /nologo $options",
     includeCmd: " /I",
-    linkDirCmd: " /LIBPATH:",
+    # HACK: we call `cl` so we have to pass `/link` for linker options,
+    # but users may still want to pass arguments to `cl` (see #14221)
+    # to deal with this, we add `/link` before each `/LIBPATH`,
+    # the linker ignores extra `/link`s since it's an unrecognized argument
+    linkDirCmd: " /link /LIBPATH:",
     linkLibCmd: " $1.lib",
     debug: " /RTC1 /Z7 ",
     pic: "",