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

This reverts commit 40fd334b2612873423051c30d6d2dd91d6081d34.

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/1279225
Reviewed-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}
2 files changed