Reland "Fixed SDK lookup for non C:\ Windows installation."

This reverts commit 864136ef.

Reason for revert:
While it seems this did trigger the cdb failures in crbug.com/846313,
it was not the root cause and reverting it didn't actually help.

Original change's description:
> Revert "Fixed SDK lookup for non C:\ Windows installation."
> 
> This reverts commit 57fd44c7.
> 
> Reason for revert: suspect for messing up symbols on Win7 bot
>                    @ crbug.com/846313
> 
> Original change's description:
> > Fixed SDK lookup for non C:\ Windows installation.
> >
> > Bug: None
> > Change-Id: Ia0aa186d1d39b1beac8ce0152683f774ad5d2eaf
> > Reviewed-on: https://chromium-review.googlesource.com/1066065
> > Reviewed-by: Jochen Eisinger <jochen@chromium.org>
> > Commit-Queue: Jochen Eisinger <jochen@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#561063}
> 
> TBR=jochen@chromium.org,yura.yaroshevich@gmail.com
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 846313
> Change-Id: Id93a965aea5555961c539d47e05e79410894eff8
> Reviewed-on: https://chromium-review.googlesource.com/1072307
> Commit-Queue: Gabriel Charette <gab@chromium.org>
> Reviewed-by: Gabriel Charette <gab@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#561609}

TBR=gab@chromium.org,jochen@chromium.org,yura.yaroshevich@gmail.com

Bug: 846313
Change-Id: I9955a47bbe8a81a0dcf7befebfc422560f8a1cc4
Reviewed-on: https://chromium-review.googlesource.com/1073314Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561873}

AUTHORS

@@ -923,6 +923,7 @@ Yumikiyo Osanai <yumios.art@gmail.com>
 Yunchao He <yunchao.he@intel.com>
 Yunsik Jang <yunsik.jang@lge.com>
 Yupei Wang <perryuwang@tencent.com>
+Yura Yaroshevich <yura.yaroshevich@gmail.com>
 Yuri Gorobets <yuri.gorobets@gmail.com>
 Yuriy Taraday <yorik.sar@gmail.com>
 Zeno Albisser <zeno.albisser@digia.com>

build/vs_toolchain.py

@@ -205,7 +205,8 @@ def _CopyUCRTRuntime(target_dir, source_dir, target_cpu, dll_pattern, suffix):
   # DEPOT_TOOLS_WIN_TOOLCHAIN=0 and vcvarsall.bat has not been run.
   win_sdk_dir = os.path.normpath(
       os.environ.get('WINDOWSSDKDIR',
-                     'C:\\Program Files (x86)\\Windows Kits\\10'))
+                     os.path.expandvars('%ProgramFiles(x86)%'
+                                        '\\Windows Kits\\10')))
   ucrt_dll_dirs = os.path.join(win_sdk_dir, 'Redist', 'ucrt', 'DLLs',
                                target_cpu)
   ucrt_files = glob.glob(os.path.join(ucrt_dll_dirs, 'api-ms-win-*.dll'))

build/win/copy_cdb_to_output.py

@@ -62,7 +62,8 @@ def _CopyCDBToOutput(output_dir, target_arch):
   # when DEPOT_TOOLS_WIN_TOOLCHAIN=0 and vcvarsall.bat has not been run.
   win_sdk_dir = os.path.normpath(
       os.environ.get('WINDOWSSDKDIR',
-                     'C:\\Program Files (x86)\\Windows Kits\\10'))
+                     os.path.expandvars('%ProgramFiles(x86)%'
+                                        '\\Windows Kits\\10')))
   if target_arch == 'ia32' or target_arch == 'x86':
     src_arch = 'x86'
   elif target_arch == 'x64':