Revert "win: Pass /pdbaltpath:%_PDB% to the linker every time we pass /DEBUG."

This reverts commit 40fd334b.

Reason for revert: It breaks the "official symbols" upload step, see
crbug.com/894991

Original change's description:
> win: Pass /pdbaltpath:%_PDB% to the linker every time we pass /DEBUG.
> 
> The linker by defaults writes the absolute path to the corresponding pdb
> into executables it creates (if /DEBUG is passed).
> 
> /pdbaltpath:%_PDB% tells it to instead just write the basename of the pdb
> into the executable, which makes the build more reproducible:
> 
> 1. Different build directories no longer cause the part of the exe that contains
>    the pdb path to be different.
> 
> 2. More subtly, the pdb file contains offsets into the executable, and if the
>    pdb path has different lengths on different systems, the pdb file will be
>    different due to the absolute pdb path in the executable.  lld-link sets the
>    UUID of the pdb to the hash of the pdb file contents, and the UUID of the
>    pdb is also stored in the executable.  So this is also one of the parts
>    needed to make the pdb output deterministic.
> 
> (Note that while link.exe has supported /pdbaltpath:%_PDB% for a long time,
> lld-link learned about %_PDB% only very recently, and this CL depends on the
> clang roll https://chromium-review.googlesource.com/c/1271718.)
> 
> Bug: 330260
> Change-Id: If4c505ababa46ed4f51330521ff09f12f6840a47
> Reviewed-on: https://chromium-review.googlesource.com/c/1273475
> Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
> Commit-Queue: Nico Weber <thakis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#598940}

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

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 330260
Change-Id: Iecb3de9f19f9d4e3932784ba9e68b00001bb8986
Reviewed-on: https://chromium-review.googlesource.com/c/1279225Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Sébastien Marchand <sebmarchand@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599398}

build/config/compiler/BUILD.gn

@@ -2182,22 +2182,6 @@ config("afdo") {
 #   configs -= [ "//build/config/compiler:default_symbols" ]
 #   configs += [ "//build/config/compiler:symbols" ]
 
-# A helper config that all configs passing /DEBUG to the linker should
-# include as sub-config.
-config("win_pdbaltpath") {
-  visibility = [
-    ":symbols",
-    ":minimal_symbols",
-  ]
-
-  # /DEBUG causes the linker to generate a pdb file, and to write the absolute
-  # path to it in the executable file it generates.  This flag turns that
-  # absolute path into just the basename of the pdb file, which helps with
-  # build reproducibility. Debuggers look for pdb files next to executables,
-  # so there's no downside to always using this.
-  ldflags = [ "/pdbaltpath:%_PDB%" ]
-}
-
 # Full symbols.
 config("symbols") {
   if (is_win) {
@@ -2228,9 +2212,6 @@ config("symbols") {
       ldflags = [ "/DEBUG" ]
     }
 
-    # All configs using /DEBUG should include this:
-    configs = [ ":win_pdbaltpath" ]
-
     if (is_clang) {
       # /DEBUG:FASTLINK requires every object file to have standalone debug
       # information.
@@ -2306,9 +2287,6 @@ config("minimal_symbols") {
     cflags = []
     ldflags = [ "/DEBUG" ]
 
-    # All configs using /DEBUG should include this:
-    configs = [ ":win_pdbaltpath" ]
-
     # For win/asan, get stack traces with full line numbers.
     # AddressSanitizerTests.TestAddressSanitizer needs this, and since
     # win/asan isn't a default cq bot the build time hit is ok.

build/config/win/BUILD.gn

@@ -139,7 +139,7 @@ config("compiler") {
   if (!is_debug && !is_component_build) {
     # Enable standard linker optimizations like GC (/OPT:REF) and ICF in static
     # release builds. These are implied by /PROFILE below, but /PROFILE is
-    # incompatible with /debug:fastlink.
+    # incompatible with /debug:fastlink and LLD ignores it as of this writing.
     # Release builds always want these optimizations, so enable them explicitly.
     # TODO(crbug.com/884545): Remove the checks for use_libfuzzer when
     # libFuzzer's issues with /OPT:REF are resolved upstream.