Set SetEnv.cmd set VSINSTALLDIR, VCINSTALLDIR

We use depot_tools's toolchain to build LLVM on the clang/win bots.
llvm-symbolizer relies on VSINSTALLDIR to be set to find the DIA SDK,
so set it.  While here, also set VCINSTALLDIR.

BUG=82385

Review URL: https://codereview.chromium.org/1604423002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@298326 0039d316-1c4b-4281-b951-d872f2087c98

win_toolchain/package_from_installed.py

@@ -183,6 +183,8 @@ def GenerateSetEnvCmd(target_dir):
     f.write('@echo off\n'
             ':: Generated by win_toolchain\\package_from_installed.py.\n'
             # Common to x86 and x64
+            'set VSINSTALLDIR=%~dp0..\\..\\\n'
+            'set VCINSTALLDIR=%~dp0..\\..\\VC\\\n'
             'set PATH=%~dp0..\\..\\Common7\\IDE;%PATH%\n'
             'set INCLUDE=%~dp0..\\..\\win_sdk\\Include\\WINVERSION\\um;'
                '%~dp0..\\..\\win_sdk\\Include\\WINVERSION\\shared;'