win: Stop deleting pdb file before links in official builds.

Reverts https://codereview.chromium.org/2519803003 , it shouldn't be needed
with lld.

(Running `ninja -t msvc` directly means ninja doesn't have to be in PATH,
since then clause 1 of how CreateProcessA() finds binaries can take effect:

1. The directory from which the application loaded.

Due to the delete, `ninja -t msvc` was run under `cmd /c`, which means we
did require ninja in PATH only for official builds. This removes this exception.
But we're also making sure ninja is in PATH for now until crbug.com/872740
is resolved, so this change is more a defense-in-depth thing.)

Bug: 665773,828472,828466
Change-Id: Ic86b255df1544fcb4744ff4d2bf1f3f0b25119c3
Reviewed-on: https://chromium-review.googlesource.com/1169302Reviewed-by: Sébastien Marchand <sebmarchand@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581905}

build/toolchain/win/BUILD.gn

@@ -143,7 +143,7 @@ template("msvc_toolchain") {
       # 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.
+      # 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 = ""
     } else {
@@ -296,21 +296,6 @@ template("msvc_toolchain") {
 
       command = "$linker_wrapper$link /nologo ${sys_lib_flags}/OUT:$exename /PDB:$pdbname @$rspfile"
 
-      if (host_os == "win") {
-        shellprefix = "cmd /c"
-      } else {
-        shellprefix = ""
-      }
-      not_needed([ "shellprefix" ])
-
-      if (is_official_build) {
-        # On bots, the binary's PDB grow and eventually exceed 4G, causing the
-        # link to fail. As there's no utility to keeping the PDB around
-        # incrementally anyway in this config (because we're doing
-        # non-incremental LTCG builds), delete it before linking.
-        command = "$shellprefix $python_path $tool_wrapper_path delete-file $pdbname && $command"
-      }
-
       default_output_extension = ".exe"
       default_output_dir = "{{root_out_dir}}"
       description = "LINK {{output}}"