Revert "win: Pass /libpath: on Windows too, and use /lldignoreenv to make lld...

Revert "win: Pass /libpath: on Windows too, and use /lldignoreenv to make lld ignore the %LIB% env var."

This reverts commit 1a693093.

Reason for revert: Apparently breaks cross builds:
https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/yhbrbPU0yLQ

Original change's description:
> win: Pass /libpath: on Windows too, and use /lldignoreenv to make lld ignore the %LIB% env var.
> 
> See https://reviews.llvm.org/D67456
> 
> Makes the build a bit more hermetic, and should have no behavior change.
> 
> Bug: none
> Change-Id: I90080aa7f8ec814e6ec9b1a4fbcad464e12a450d
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1807154
> Auto-Submit: Nico Weber <thakis@chromium.org>
> Commit-Queue: Reid Kleckner <rnk@chromium.org>
> Reviewed-by: Reid Kleckner <rnk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#697369}

TBR=thakis@chromium.org,rnk@chromium.org

Change-Id: Idccc2a0bd54f6543734bf6f24a5cd73bbe0295d2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: none
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1808036Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697397}

build/config/win/BUILD.gn

@@ -142,9 +142,6 @@ config("compiler") {
     # (link.exe also writes the current time, but it doesn't have a flag to
     # override that behavior.)
     ldflags += [ "/TIMESTAMP:" + build_timestamp ]
-
-    # Don't look for libpaths in %LIB%, similar to /X in cflags above.
-    ldflags += [ "/lldignoreenv" ]
   }
 
   if (!is_debug && !is_component_build) {

build/toolchain/win/BUILD.gn

@@ -130,17 +130,17 @@ template("msvc_toolchain") {
 
     # ninja does not have -t msvc other than windows, and lld doesn't depend on
     # mt.exe in PATH on non-Windows, so it's not needed there anyways.
-    if (host_os != "win") {
+    if (defined(invoker.sys_lib_flags)) {
       linker_wrapper = ""
       sys_lib_flags = "${invoker.sys_lib_flags} "  # Note trailing space
-    } else if (defined(invoker.sys_lib_flags)) {
+    } else if (use_lld) {
       # Invoke ninja as wrapper instead of tool wrapper, because python
       # invocation requires higher cpu usage compared to ninja invocation, and
       # the python wrapper is only needed to work around link.exe problems.
       # TODO(thakis): Remove wrapper once lld-link can merge manifests without
       # relying on mt.exe being in %PATH% on Windows, https://crbug.com/872740
       linker_wrapper = "ninja -t msvc -e $env -- "  # Note trailing space.
-      sys_lib_flags = "${invoker.sys_lib_flags} "  # Note trailing space
+      sys_lib_flags = ""
     } else {
       linker_wrapper =
           "$python_path $tool_wrapper_path link-wrapper $env False "  # Note trailing space.
@@ -359,6 +359,10 @@ template("win_toolchains") {
   msvc_toolchain(target_name) {
     environment = "environment." + toolchain_arch
     cl = "${goma_prefix}\"${win_toolchain_data.vc_bin_dir}/cl.exe\""
+    if (host_os != "win") {
+      # For win cross build
+      sys_lib_flags = "${win_toolchain_data.libpath_flags}"
+    }
 
     toolchain_args = {
       if (defined(invoker.toolchain_args)) {
@@ -379,7 +383,10 @@ template("win_toolchains") {
       cl = string_replace(cl, "/", "\\")
     }
     sys_include_flags = "${win_toolchain_data.include_flags_imsvc}"
-    sys_lib_flags = "${win_toolchain_data.libpath_flags}"
+    if (host_os != "win") {
+      # For win cross build
+      sys_lib_flags = "${win_toolchain_data.libpath_flags}"
+    }
 
     toolchain_args = {
       if (defined(invoker.toolchain_args)) {